Summary
Plan status as of 2026-09-30: Approved, expires 2026-12-09. Plan: Mercer County 2021 (FEMA plan 107821), approved 2021-12-10.
Update: FEMA tracker shows a plan in progress.
Since the plan was approved on 2021-12-10: no new hazard declaration and 98 NOAA Storm Events records; details under "What changed since your last plan".
Highest expected annual loss (FEMA National Risk Index, modeled total; see B1-a): Inland Flooding ($113,557,638 a year), Hurricane ($18,127,303) and Strong Wind ($12,731,528).
The tables that follow are organized by the items of FEMA's Local Mitigation Plan Review Tool, Element B (B1-a to B2-c); each heading says which item its tables support.
Plan clock
- Status:
- Approved, expires 2026-12-09
- Plan:
- Mercer County 2021 (FEMA plan 107821)
- Approved:
- 2021-12-10
- Days to expiry:
- 70
- Update underway:
- FEMA tracker shows a plan in progress
What changed since your last plan (approved 2021-12-10)
- New federal declarations:
- none
- Storm Events records since approval:
- 98 records (data through 2026-06-30)
- Repetitive loss now:
- FMA RL 10, SRL 36 (44 CFR 77.2); any definition: 313
- Repeat-flood change:
- this release sets the baseline count.
Sources: 1, 2, 4, 6 (numbered list at the end)
Plan status for every jurisdiction listed in this county: 13 rows, in the section "Plan clock: Plan status for every jurisdiction listed in this county" on the following pages.
State plan status and tribal plans in this state: see the state page.
Plan clock
Plan status for every jurisdiction listed in this county
Source: 1
| Jurisdiction | Type | Status | Plan | Approved | Expires | Days to expirynegative = days since expiry | Update underway | Notes |
|---|---|---|---|---|---|---|---|---|
| Mercer County | County | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2021-12-29 |
| Hightstown borough | Borough | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-02-09 |
| Hopewell borough | Borough | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-14 |
| Pennington borough | Borough | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-04 |
| Princeton | Borough | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-04 |
| Trenton city | City | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-31 |
| East Windsor township | Township | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-24 |
| Ewing township | Township | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2021-12-16 |
| Hamilton township | Township | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-03-04 |
| Hopewell township | Township | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-18 |
| Lawrence township | Township | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | |
| Robbinsville township | Township | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-28 |
| West Windsor township | Township | Approved, expires 2026-12-09 | Mercer County 2021 (FEMA plan 107821) | 2021-12-10 | 2026-12-09 | 70 | FEMA tracker shows a plan in progress | this jurisdiction approved 2022-01-20 |
Supports FEMA checklist item B1-a: hazard identification
Hazards NRI does not cover (local data needed)
- dam failure (incl. upstream dams)
- levee failure
- flash flood as its own subtype
- ice jams
- debris flows
- erosion (riverine and coastal)
- land subsidence and sinkholes
- expansive soils
The 18 National Risk Index hazards, ranked by expected annual loss (EAL)
Sources: 5, 6
| Rank by EAL | Hazard | NRI risk rating | EAL rating | EAL buildingsmodeled dollars per year | EAL agriculturemodeled dollars per year | Cost of expected deaths and injuriesFEMA's dollar value per year, not property damage | EAL total (see note)modeled dollars per year | Storm Events records, 1996 to 2026-06-30count | Storm Events coverage note |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Inland Flooding | Relatively High | Relatively High | $108,143,494 | $47,171 | $5,366,973 | $113,557,638 | 126 | |
| 2 | Hurricane | Relatively High | Relatively High | $17,435,955 | $151,772 | $539,576 | $18,127,303 | 3 | |
| 3 | Strong Wind | Very High | Very High | $9,120,944 | $5,011 | $3,605,573 | $12,731,528 | 360 | Includes 35 High Wind and 93 Strong Wind records (NOAA non-thunderstorm wind types, outside NRI's Strong Wind definition). |
| 4 | Earthquake | Relatively Moderate | Relatively Moderate | $7,429,144 | n/a | $3,164,505 | $10,593,649 | Storm Events does not record earthquakes. | |
| 5 | Heat Wave | Relatively Moderate | Relatively Moderate | under $1 | $98 | $6,829,255 | $6,829,353 | 92 | |
| 6 | Cold Wave | Relatively Moderate | Relatively High | $262 | $8 | $4,831,864 | $4,832,134 | 31 | Includes 2 Frost/Freeze records (outside NRI's Cold Wave definition; counted in this table and in B1-d, not in the B1-e descriptor). |
| 7 | Tornado | Relatively Moderate | Relatively Moderate | $1,856,319 | $274 | $2,247,990 | $4,104,583 | 11 | |
| 8 | Ice Storm | Very High | Very High | $1,665,845 | n/a | $190,470 | $1,856,316 | 0 | No recorded events in Storm Events since 1996 (data through 2026-06-30). |
| 9 | Lightning | Relatively High | Relatively High | $109,268 | n/a | $1,361,277 | $1,470,545 | 38 | |
| 10 | Winter Weather | Very High | Very High | $208,144 | $10 | $929,074 | $1,137,228 | 224 | Includes 3 Sleet records (outside NRI's Winter Weather definition). |
| 11 | Coastal Flooding | Relatively Low | Relatively Low | $326,656 | n/a | $2,579 | $329,235 | 11 | |
| 12 | Drought | Relatively Low | Relatively Low | n/a | $304,640 | n/a | $304,640 | 44 | |
| 13 | Wildfire | Relatively Low | Relatively Low | $187,717 | $28 | $28,181 | $215,926 | 6 | |
| 14 | Hail | Very Low | Very Low | $49,694 | $23,289 | $37,234 | $110,217 | 52 | |
| 15 | Landslide | Very Low | Very Low | $1,593 | n/a | $15 | $1,608 | 0 | No recorded events in Storm Events since 1996 (data through 2026-06-30). |
Total = buildings + agriculture + population equivalence; FEMA values each expected death (or 10 injuries) at $13.7 million (2024 dollars).
NRI risk rating combines expected annual loss with social vulnerability and community resilience; EAL rating rates expected annual loss alone. Both compare this county with all U.S. counties.
Local data needed: state and local landslide records (Storm Events records this hazard only in part).
Not applicable to this county per NRI, with no federal declaration and no Storm Events record since 1996: avalanche, tsunami and volcanic activity. That is the evidence for leaving them out of the plan.
The state hazard mitigation plan also lists hazards for this county; FEMA asks the plan to explain any hazard it leaves out.
Supports FEMA checklist item B1-b: hazard location
Affects the whole county (national data give no location within it): Cold Wave, Drought, Hail, Heat Wave, Ice Storm, Lightning, Strong Wind and Winter Weather.
Coastal Flooding and Inland Flooding: The FEMA Flood Insurance Rate Map (FIRM) is the required location source for flooding. See the FEMA Flood Map Service Center (https://msc.fema.gov) for this county.
Hazards that vary within the county: highest-rated census tracts
Source: 5
| Hazard | Highest-rated census tractsNRI risk rating, score 0 to 100 |
|---|---|
| Earthquake | tract 9 (Relatively Moderate, 87.3); tract 37.03 (Relatively Moderate, 82.9); tract 30.03 (Relatively Moderate, 82.9) |
| Hurricane | tract 30.03 (Relatively High, 90.2); tract 9 (Relatively High, 90.1); tract 11.01 (Relatively Moderate, 89.3) |
| Landslide | tract 38 (Relatively Low, 91.6); tract 39.05 (Very Low, 78.8); tract 42.03 (Very Low, 73.5) |
| Tornado | tract 30.03 (Relatively Moderate, 60.1); tract 44.04 (Relatively Moderate, 57.0); tract 9 (Relatively Moderate, 56.1) |
| Wildfire | tract 30.03 (Relatively Low, 86.6); tract 30.01 (Relatively Low, 86.6); tract 44.06 (Relatively Low, 84.6) |
Up to 3 census tracts per hazard, highest National Risk Index rating first, then highest score; a tract number is the Census tract number (for example 9 is Census Tract 9). FEMA's Resilience Analysis and Planning Tool maps the National Risk Index for every tract: https://www.fema.gov/emergency-managers/practitioners/resilience-analysis-and-planning-tool
Supports FEMA checklist item B1-c: hazard extent
Extent: scale, observed range and worst recorded event per hazard
Sources: 6, 7
| Hazard | Scale | Recordscount and years | Observed range | Worst recorded event | Most damaging (when different) | How it applies to jurisdictions | Note |
|---|---|---|---|---|---|---|---|
| Coastal Flood, Storm Surge/Tide | none in data (flood depth: FIRM) | 11 records, 2012 to 2024 (11 zone-level) | Coastal Flood, 2012-10-30, $1,000,000 property; $0 crops (2012 dollars); NWS zone NJZ015 | Countywide (zone-level records). | Flood depth: see the FEMA Flood Insurance Rate Map. | ||
| Cold/Wind Chill, Extreme Cold/Wind Chill | wind chill | 29 records, 1996 to 2022 (29 zone-level) | 1 day to 16 days (median 1.5 days); 24 with a recorded value | 16 consecutive days, 2003-01-14 to 2003-01-29, zone-level | Countywide (zone-level records). | Cold/Wind Chill records from May to September (a frost night, not a cold wave) are counted but not used for the longest run. | |
| Frost/Freeze (outside NRI's Cold Wave definition) | crop damage | 2 records, 2007 (2 zone-level) | No crop damage reported in 2 records. | Countywide (zone-level records). | |||
| Drought | U.S. Drought Monitor scale (D0 to D4) | 44 records, 1997 to 2015 (44 zone-level) | 1 day to 392 days (median 2 days); 19 with a recorded value | 392 days (about 12.9 months), 2001-10-30 to 2002-11-25, a run of 14 consecutive Storm Events drought records, zone-level | Countywide (zone-level records). | Storm Events enters a drought at D2 or worse east of the Rockies and D3 or worse from the Rockies west (NWS Instruction 10-1605); NRI drought counts D3 and D4 only. | |
| Earthquake | Modified Mercalli (local data) | 0 | Storm Events does not record earthquakes; the USGS earthquake catalog is the source. | ||||
| Hail | hail size (inches) | 63 records, 1974 to 2023 | 0.75 in to 1.75 in (median 1 in); 62 with a recorded value | 1.75 in hail, 2008-07-23; same size also recorded on 1980-06-03, 1985-06-24, 1987-06-13, 2000-10-04 | Event records naming jurisdictions in the plan: Princeton (5 records), Pennington borough (4 records), Hopewell borough (3 records), Hopewell township (3 records), East Windsor township (1 record), Robbinsville township (1 record). | ||
| Excessive Heat, Heat | heat index (in event narratives) | 92 records, 1996 to 2025 (92 zone-level) | 1 day to 10 days (median 2 days); 69 with a recorded value | 10 consecutive days, 2002-08-11 to 2002-08-20, zone-level | Countywide (zone-level records). | Heat records from November to March (unseasonable warmth, not a heat wave) are counted but not used for the longest run. | |
| Hurricane, Tropical Storm, Tropical Depression | Saffir-Simpson | 3 records, 2008 to 2020 (3 zone-level) | Strongest recorded: Tropical Storm record, 2011-08-27 to 2011-08-28, $500,000 property; $0 crops (2011 dollars); NWS zone NJZ015 | Countywide (zone-level records). | Storm Events files every zone of a storm's episode under the storm's type; flooding from the storm is filed as Flood or Flash Flood records. | ||
| Ice Storm | Sperry-Piltz ice scale (local data) | 0 | |||||
| Flash Flood, Flood, Lakeshore Flood | damage and flood days (flood depth: FIRM) | 126 records, 1996 to 2026 (20 zone-level) | Flood, 2011-08-28, $75,000,000 property; $0 crops (2011 dollars), 2 direct deaths | Event records naming jurisdictions in the plan: Trenton city (14 records), Princeton (10 records), East Windsor township (4 records), Pennington borough (3 records), Hightstown borough (1 record), Hopewell borough (1 record), Hopewell township (1 record), Robbinsville township (1 record). Zone-level records (20) apply countywide. | Flood depth: see the FEMA Flood Insurance Rate Map. Storm Events damage is often $0 or blank for floods, major ones included; FEMA Public Assistance by declaration (B1-d) shows which floods cost the most. | ||
| Debris Flow | none (count and damage only) | 0 | |||||
| Lightning | annualized frequency (the measure FEMA's Local Mitigation Planning Handbook names) | 38 records, 1997 to 2020 | Lightning, 2014-07-02, $1,000,000 property; $0 crops (2014 dollars) | Event records naming jurisdictions in the plan: Princeton (7 records), Trenton city (3 records), East Windsor township (2 records), Hopewell borough (2 records), Hopewell township (2 records), Hightstown borough (1 record), Pennington borough (1 record), Robbinsville township (1 record). | Storm Events lists lightning with damage or casualties. | ||
| High Wind and Strong Wind (outside NRI's Strong Wind definition) | wind speed (kt and mph) | 128 records, 1996 to 2025 (128 zone-level) | 35 kt (40 mph) to 61 kt (70 mph) (median 40 kt (46 mph)); 100 with a recorded value | 61 kt (70 mph), measurement type not recorded, High Wind, 1999-01-18; NWS zone NJZ015 | High Wind, 2012-10-29, $100,000,000 property; $0 crops (zone total, 2012 dollars) | Countywide (zone-level records). | |
| Thunderstorm Wind | wind speed (kt and mph) | 275 records, 1955 to 2026 | 49 kt (56 mph) to 69 kt (79 mph) (median 50 kt (58 mph)); 233 with a recorded value | 69 kt (79 mph) estimated, Thunderstorm Wind, 2000-10-04, 3 direct injuries | Thunderstorm Wind, 2010-08-16, $1,000,000 property; $0 crops (2010 dollars) | Event records naming jurisdictions in the plan: Princeton (23 records), Hopewell borough (19 records), Hopewell township (19 records), Trenton city (18 records), East Windsor township (10 records), Pennington borough (8 records), Hightstown borough (4 records), Robbinsville township (4 records), Ewing township (1 record). | |
| Tornado | Enhanced Fujita (Fujita before Feb 2007) | 18 records, 1958 to 2024 | F/EF0 to F/EF2 (median F/EF1); 17 with a recorded value | F2 tornado, 1962-05-24, 14.7 mi path length (whole path, pre-1996), 300 yd wide, $250,000 property; crops not recorded (1962 dollars), 1 direct injury | Tornado, 1988-08-17, $2,500,000 property; crops not recorded (1988 dollars) | Event records naming jurisdictions in the plan: Hightstown borough (3 records), Trenton city (2 records). | Before 1996 a tornado is listed once, under the county where it began, with its whole path's rating and length; from 1996 on, each county lists its own segment. Length is not used to rank tornadoes (see Methods). |
| Wildfire | acres burned (local data) | 6 records, 2001 to 2012 (5 zone-level) | No damage reported in 6 records. | No event record names a jurisdiction in the plan. Zone-level records (5) apply countywide. | |||
| Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleet | none in data (snowfall: local data) | 224 records, 1996 to 2026 (224 zone-level) | Blizzard, 1996-01-07, $1,100,000 property; crops not reported (1996 dollars), 1 direct death (reported for the zone); NWS zone NJZ015 | Countywide (zone-level records). |
In event narratives only (local data needed): wind chill, temperature, heat index, ice thickness, acres burned and snow depth; any physical measure of debris flow and lightning.
Storm Events records are more complete after 1996; before 1996 only Tornado (from 1950), Hail and Thunderstorm Wind (from 1955) exist. Zone-level records from zones that no NWS zone-county file places in this county (mostly before 2020) are not counted here (the Methods page explains the zone matching).
Dollars are nominal (as reported), labeled with the year; not adjusted for inflation.
Supports FEMA checklist item B1-d: previous occurrences
Federal declarations for this county: 28 declarations covering 19 separate hazard incidents counted in this packet (declarations for the same incident count once; non-natural and evacuation-only declarations are not counted).
Federal disaster declarations for this county
Sources: 1, 2, 3
| Declared | Incident began | FEMA number | Type | Title | Mapped hazard | County Public Assistancefederal share obligated, nominal dollars | Flags | Notes |
|---|---|---|---|---|---|---|---|---|
| 2021-09-05 | 2021-09-01 | DR-4614-NJ | Major disaster | Remnants of Hurricane Ida | Hurricane | $5,758,837.58 | in the 12 months before plan approval | |
| 2021-09-02 | 2021-09-01 | EM-3573-NJ | Emergency | Remnants of Hurricane Ida | Hurricane | no Public Assistance recorded | in the 12 months before plan approval | same incident as DR-4614 |
| 2020-03-25 | 2020-01-20 | DR-4488-NJ | Major disaster | COVID-19 Pandemic | Non-natural, not counted | $26,635,718.40 | ||
| 2020-03-13 | 2020-01-20 | EM-3451-NJ | Emergency | COVID-19 | Non-natural, not counted | no Public Assistance recorded | same incident as DR-4488 | |
| 2016-03-14 | 2016-01-22 | DR-4264-NJ | Major disaster | Severe Winter Storm and Snowstorm | Winter Weather | $1,905,198.35 | ||
| 2012-10-30 | 2012-10-26 | DR-4086-NJ | Major disaster | Hurricane Sandy | Hurricane | $11,619,416.46 | ||
| 2012-10-28 | 2012-10-26 | EM-3354-NJ | Emergency | Hurricane Sandy | Hurricane | no Public Assistance recorded | same incident as DR-4086 | |
| 2011-10-14 | 2011-09-28 | DR-4039-NJ | Major disaster | Remnants of Tropical Storm Lee | Hurricane | $229,621.81 | ||
| 2011-08-31 | 2011-08-27 | DR-4021-NJ | Major disaster | Hurricane Irene | Hurricane | $4,871,101.77 | ||
| 2011-08-27 | 2011-08-26 | EM-3332-NJ | Emergency | Hurricane Irene | Hurricane | no Public Assistance recorded | same incident as DR-4021 | |
| 2011-02-04 | 2010-12-26 | DR-1954-NJ | Major disaster | Severe Winter Storm and Snowstorm | Winter Weather | $1,294,861.47 | ||
| 2010-04-02 | 2010-03-12 | DR-1897-NJ | Major disaster | Severe Storms and Flooding | Inland Flooding | $997,256.82 | ||
| 2007-04-26 | 2007-04-14 | DR-1694-NJ | Major disaster | Severe Storms and Inland and Coastal Flooding | Coastal Flooding | $349,225.75 | ||
| 2006-07-07 | 2006-06-23 | DR-1653-NJ | Major disaster | Severe Storms and Flooding | Inland Flooding | $589,410.31 | ||
| 2005-09-19 | 2005-08-29 | EM-3257-NJ | Emergency | Hurricane Katrina Evacuation | Hurricane: evacuation support, not a local hazard event; not counted | no Public Assistance recorded | ||
| 2005-04-19 | 2005-04-01 | DR-1588-NJ | Major disaster | Severe Storms and Flooding | Inland Flooding | PA not declared for this county | ||
| 2004-10-01 | 2004-09-18 | DR-1563-NJ | Major disaster | Severe Storms and Flooding | Inland Flooding | $268,975 | ||
| 2003-03-20 | 2003-02-16 | EM-3181-NJ | Emergency | Snow | Winter Weather | $741,182.19 | ||
| 2001-09-19 | 2001-09-11 | EM-3169-NJ | Emergency | Fires and Explosions | Non-natural, not counted | $150,097.55 | ||
| 2000-11-01 | 2000-05-30 | EM-3156-NJ | Emergency | West Nile Virus | Non-natural, not counted | no Public Assistance recorded | ||
| 1999-09-18 | 1999-09-16 | DR-1295-NJ | Major disaster | Hurricane Floyd Major Disaster Declarations | Hurricane | $507,089.20 | ||
| 1999-09-17 | 1999-09-16 | EM-3148-NJ | Emergency | Hurricane Floyd Emergency Declarations | Hurricane | no Public Assistance recorded | same incident as DR-1295 | |
| 1996-01-13 | 1996-01-07 | DR-1088-NJ | Major disaster | Blizzard of 96 (Severe Snow Storm) | Winter Weather | no Public Assistance recorded | ||
| 1993-03-17 | 1993-03-13 | EM-3106-NJ | Emergency | Severe Blizzard | Winter Weather | no Public Assistance recorded | ||
| 1980-10-19 | 1980-10-19 | EM-3083-NJ | Emergency | Water Shortage | Drought | no Public Assistance recorded | ||
| 1975-07-23 | 1975-07-23 | DR-477-NJ | Major disaster | Heavy Rains, High Winds, Hail & Tornadoes | Inland Flooding (primary); also designated: Hail, Strong Wind, Tornado | no Public Assistance recorded | ||
| 1971-09-04 | 1971-09-04 | DR-310-NJ | Major disaster | Heavy Rains & Flooding | Inland Flooding | no Public Assistance recorded | ||
| 1965-08-18 | 1965-08-18 | DR-205-NJ | Major disaster | Water Shortage | Drought | no Public Assistance recorded |
County Public Assistance: applicants the FEMA record places in this county, including any state agencies FEMA files there; statewide rows are listed on the state page; federal share obligated, nominal dollars.
Statewide declarations
Source: 2
| Declared | Incident began | FEMA number | Type | Title | Mapped hazard |
|---|---|---|---|---|---|
| 1962-03-09 | 1962-03-09 | DR-124-NJ | Major disaster | Severe Storm, High Tides & Flooding | Inland Flooding (primary); also designated: Coastal Flooding |
| 1955-08-20 | 1955-08-20 | DR-41-NJ | Major disaster | Hurricane & Floods | Hurricane (primary); also designated: Inland Flooding |
FEMA recorded these with designated area Statewide and no county, so they are listed on every county page in the state and not counted with county rows. Local data needed: whether each one affected this county.
Public Assistance not placed in any New Jersey county: 1 row, $23,724.37; listed on the New Jersey state page.
Source: 3
Previous occurrences by hazard, with explicit no-event rows
Sources: 2, 6, 7
| Hazard | Storm Events records, all years on file(years in the Period column) | Since plan approvalrecords | In the 12 months before plan approvalrecords | Last 5 yearsrecords | Declared incidents, all yearsseparate disasters | Declared since approvalseparate disasters | Period | Statement |
|---|---|---|---|---|---|---|---|---|
| Coastal Flooding | 11 | 4 | 3 | 5 | 1 | 0 | 1996 to 2026-06-30 | |
| Cold Wave | 31 | 1 | 0 | 1 | 0 | 0 | 1996 to 2026-06-30 | Includes 2 Frost/Freeze records. |
| Drought | 44 | 0 | 0 | 0 | 2 | 0 | 1996 to 2026-06-30 | |
| Earthquake | 0 | 0 | 0 | 0 | 0 | 0 | Storm Events does not record earthquakes; the USGS earthquake catalog is the source. | |
| Hail | 63 | 9 | 2 | 9 | 1 | 0 | 1955 to 2026-06-30 | |
| Heat Wave | 92 | 6 | 2 | 6 | 0 | 0 | 1996 to 2026-06-30 | |
| Hurricane | 3 | 0 | 0 | 0 | 5 | 0 | 1996 to 2026-06-30 | |
| Ice Storm | 0 | 0 | 0 | 0 | 0 | 0 | 1996 to 2026-06-30 | No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events |
| Inland Flooding | 126 | 5 | 12 | 6 | 6 | 0 | 1996 to 2026-06-30 | |
| Landslide | 0 | 0 | 0 | 0 | 0 | 0 | 1996 to 2026-06-30 | No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events |
| Lightning | 38 | 0 | 0 | 0 | 0 | 0 | 1996 to 2026-06-30 | |
| Strong Wind | 403 | 46 | 16 | 47 | 1 | 0 | 1955 to 2026-06-30 | Includes 35 High Wind and 93 Strong Wind records. |
| Tornado | 18 | 4 | 3 | 4 | 1 | 0 | 1950 to 2026-06-30 | |
| Wildfire | 6 | 0 | 0 | 0 | 0 | 0 | 1996 to 2026-06-30 | |
| Winter Weather | 224 | 23 | 10 | 23 | 5 | 0 | 1996 to 2026-06-30 | Includes 3 Sleet records. |
Notable Storm Events records
Sources: 1, 6, 7
| Date | Event type | Magnitude or extent | Damagenominal dollars | Deaths, injuriesdirect only | Location | Flags | Why listed |
|---|---|---|---|---|---|---|---|
| 2021-09-01 | Flash Flood | $50,000,000 property; $1,000,000 crops (2021 dollars) | 2, 0 | TITUSVILLE to WHITE HORSE | in the 12 months before plan approval | deaths or injuries recorded | |
| 2014-07-02 | Lightning | $1,000,000 property; $0 crops (2014 dollars) | 0, 0 | EAST WINDSOR | B1-c worst recorded: Lightning | ||
| 2012-10-29 | High Wind | 59 kt (68 mph) measured gust | $100,000,000 property; $0 crops (zone total, 2012 dollars) | 2, 0 | NWS zone NJZ015 (MERCER), zone-level | deaths or injuries recorded | |
| 2011-08-28 | Flood | $75,000,000 property; $0 crops (2011 dollars) | 2, 0 | HOPEWELL to TITUSVILLE | B1-c worst recorded: Flash Flood, Flood, Lakeshore Flood | ||
| 2011-08-27 | Tropical Storm | $500,000 property; $0 crops (zone total, 2011 dollars) | 0, 0 | NWS zone NJZ015 (MERCER), zone-level | B1-c worst recorded: Hurricane, Tropical Storm, Tropical Depression | ||
| 2003-01-14 | Cold/Wind Chill | damage not reported | 0, 0 | NWS zone NJZ015 (MERCER), zone-level | B1-c worst recorded: Cold/Wind Chill, Extreme Cold/Wind Chill | ||
| 2002-08-11 | Heat | damage not reported | 0, 0 | NWS zone NJZ015 (MERCER), zone-level | B1-c worst recorded: Excessive Heat, Heat | ||
| 2000-10-04 | Thunderstorm Wind | 69 kt (79 mph) estimated | $250,000 property; $100,000 crops (2000 dollars) | 0, 3 | LAWRENCEVILLE | B1-c worst recorded: Thunderstorm Wind | |
| 1999-07-04 | Heat | damage not reported | 3, 0 | NWS zone NJZ015 (MERCER), zone-level | deaths or injuries recorded | ||
| 1999-01-18 | High Wind | 61 kt (70 mph), measurement type not recorded | $750,000 property; $0 crops (zone total, 1999 dollars) | 0, 0 | NWS zone NJZ015 (MERCER), zone-level | B1-c worst recorded: High Wind and Strong Wind | |
| 1996-01-07 | Blizzard | $1,100,000 property; crops not reported (zone total, 1996 dollars) | 1, 0 | NWS zone NJZ015 (MERCER), zone-level | B1-c worst recorded: Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleet | ||
| 1962-05-24 | Tornado | F2, 14.7 mi path length (whole path, pre-1996), 300 yd wide | $250,000 property; crops not recorded (1962 dollars) | 0, 1 | location not recorded | B1-c worst recorded: Tornado |
The full list is in the Excel file, sheet "B1-d Storm Events history" (1,059 rows).
Location is the place NOAA recorded, as written in its data; it need not be a jurisdiction in this plan.
Local data needed: state-declared emergencies, from your state emergency management agency (federal data do not include them).
Tribal and special-area declarations in this state are listed on the state page.
Supports FEMA checklist item B1-e: probability of future events
Probability: FEMA annualized frequency and descriptor per hazard
Sources: 5, 6
| Hazard | FEMA annualized frequency (modeled)unit per row | Unit | In plain terms | Descriptor | Descriptor basis | NRI events or days in its record period (hail, wind and tornado are area-weighted, so can be fractional) | NRI period | Location | Note |
|---|---|---|---|---|---|---|---|---|---|
| Coastal Flooding | 6.17 | events per year at a location (modeled) | about 6.2 per year at a given location in the county | Highly likely | FEMA annualized frequency (modeled) | not shown | modeled | see B1-f | Descriptor from NRI: the rate at a location is 1 or more a year, so the county rate is at least that. |
| Cold Wave | 0.843 | event-days per year | about 0.843 days per year | Likely | Storm Events event-days in 13 of 30 years, 1996 to 2025 (43.3%) | 16 | 2005-11-12 to 2024-11-12 (19 years) | countywide | |
| Drought | 3.22 | event-days per year | about 3.22 days per year | Likely | Storm Events event-days in 10 of 30 years, 1996 to 2025 (33.3%) | 119 | 2000 to 2025 (25.25 years; D3 and D4 only) | countywide | |
| Earthquake | 0.00188 | annual probability at a location | chance a given location in the county has at least minor-damage shaking in a year: 0.188% | not shown | modeled | see B1-f | No descriptor (Storm Events does not record earthquakes). | ||
| Hail | 2.4 | events per year | about 2.4 per year | Highly likely | FEMA annualized frequency (modeled) | 91.4 (modeled) | 1986 to 2023 (38 years) | countywide | |
| Heat Wave | 11 | event-days per year | about 11 days per year | Likely | Storm Events event-days in 25 of 30 years, 1996 to 2025 (83.3%) | 123 | 2005-11-12 to 2024-11-12 (19 years) | countywide | |
| Hurricane | 0.115 | events per year | about 1 in 9 years | Likely | FEMA annualized frequency (modeled) | 28 | 1851 to 2024 (Atlantic) | see B1-f | NRI counts hurricane and tropical storm tracks passing within storm-force wind range; federal declarations are in B1-d. |
| Ice Storm | 1.09 | event-days per year | about 1.09 days per year | Storm Events event-days in 0 of 30 years, 1996 to 2025 (0%) | 74 | 1946-12-31 to 2014-02-12 (67 years) | countywide | No Storm Events ice storm record, 1996 to 2025 | |
| Inland Flooding | 3.64 | event-days per year | about 3.64 days per year | Highly likely | Storm Events event-days in 27 of 30 years, 1996 to 2025 (90%) | 102 | 1996 to 2023 (28 years) | see B1-f | |
| Landslide | 0.0655 | events per year (modeled) | about 1 in 15 years | Possible | FEMA annualized frequency (modeled) | not shown | modeled | see B1-f | |
| Lightning | 33.6 | days per year with a strike | about 33.6 days per year | Highly likely | FEMA annualized frequency (modeled) | not shown | 1995 to 2023 (29 years; CONUS) | countywide | |
| Strong Wind | 7.02 | events per year | about 7.02 per year | Highly likely | FEMA annualized frequency (modeled) | 267 | 1986 to 2023 (38 years) | countywide | |
| Tornado | 0.0883 | events per year | about 1 in 11 years | Possible | FEMA annualized frequency (modeled) | not shown | 1950 to 2023 (EF2+); 1986 to 2023 (EF0-1) | see B1-f | |
| Wildfire | 0.000537 | annual probability at a location | chance a given location in the county burns in a year: 0.0537% | Likely | Storm Events records in 3 of 30 years, 1996 to 2025 (10%) | not shown | modeled | see B1-f | |
| Winter Weather | 10.6 | event-days per year | about 10.6 days per year | Highly likely | Storm Events event-days in 29 of 30 years, 1996 to 2025 (96.7%) | 202 | 2005-11-12 to 2024-11-12 (19 years) | countywide |
FEMA annualized frequency (modeled) is the National Risk Index v1.20 (December 2025) estimate of how often a hazard affects this county in a year; it is not recorded events divided by years, and its unit differs by hazard (events, event-days, or days with a lightning strike per year). For earthquake, wildfire, coastal flooding and tsunami the value is the chance (or number of events) at a location in the county, not across the county, so no "1 in N years" is given and the descriptor comes from Storm Events where it has a record (none for earthquake). The Methods page gives each hazard's method, from FEMA's National Risk Index Technical Documentation v1.20.
Where NRI gives event-days, the descriptor comes from the share of years with a Storm Events record; NRI's source records more events, so the two differ.
Descriptor scale used in this packet (defined per unit)
Sources: 5, 6
| Unit | Descriptor | Definition |
|---|---|---|
| events per year | Highly likely | 1 or more per year |
| events per year | Likely | about once in 1 to 10 years |
| events per year | Possible | about once in 10 to 100 years |
| events per year | Unlikely | less than once in 100 years |
| annual probability | Likely | 10% to under 100% chance in a given year |
| annual probability | Possible | 1% to under 10% chance in a given year |
| annual probability | Unlikely | under 1% chance in a given year |
| event-days (share of years) | Highly likely | event-days recorded in 90% or more of years |
| event-days (share of years) | Likely | event-days recorded in 10% to under 90% of years |
| event-days (share of years) | Possible | event-days recorded in some years but under 10% of years |
| lightning strike-days | Highly likely | cloud-to-ground strikes on 1 or more days per year |
Intensity bands: historical frequency (Storm Events)
Source: 6
| Hazard | Band | Years | Eventscounty-coded records | Years in period | Events per yearevents / years |
|---|---|---|---|---|---|
| Hail | 1.00-1.99 in | 1996 to 2025 | 28 | 30 | 0.933 |
| Hail | 2.00 in+ | 1996 to 2025 | 0 | 30 | 0 |
| Thunderstorm Wind (counted as NRI Strong Wind) | 50-64 kt | 1996 to 2025 | 205 | 30 | 6.83 |
| Thunderstorm Wind (counted as NRI Strong Wind) | 65 kt+ | 1996 to 2025 | 1 | 30 | 0.0333 |
| Thunderstorm Wind (counted as NRI Strong Wind) | unmeasured or below 50 kt | 1996 to 2025 | 12 | 30 | 0.4 |
| Tornado | EF0-1 | 1996 to 2025 | 9 | 30 | 0.3 |
| Tornado | EF2-3 | 1996 to 2025 | 2 | 30 | 0.0667 |
| Tornado | EF4-5 | 1996 to 2025 | 0 | 30 | 0 |
| Tornado | unrated (EFU) | 1996 to 2025 | 0 | 30 | 0 |
The bands show how often events of each severity were recorded in this county, to profile how severe events have been (FEMA's probability item asks for the range of intensities).
Hail smaller than 1 inch is not counted: on 2010-01-05 the National Weather Service raised its severe-hail threshold from 3/4 inch to 1 inch, so smaller reports became less common after 2009 (NWS Service Change Notice 09-52). NRI hail frequency uses a 0.75 inch threshold.
Optional: future conditions. Not a required item in the 2025 FEMA Local Mitigation Planning Policy Guide; some states ask for it. The federal Climate Mapping for Resilience and Adaptation (CMRA) site gives county exposure to future climate conditions (https://resilience.climate.gov/).
Supports FEMA checklist item B1-f: hazards that vary across jurisdictions
Range of census tract risk within the county
Source: 5
| Hazard | Tractsrated of all | NRI risk score, 0 to 100 | Tracts by rating | ||
|---|---|---|---|---|---|
| Min | Median | Max | |||
| Coastal Flooding | 5 of 84 | 85.7 | 93.1 | 96.8 | Relatively High 1, Relatively Moderate 3, Relatively Low 1, No Rating 79 |
| Cold Wave | 84 of 84 | 25.9 | 54.3 | 72.4 | Relatively Moderate 59, Relatively Low 25 |
| Drought | 46 of 84 | 68.9 | 78.8 | 93.3 | Relatively Moderate 2, Relatively Low 20, Very Low 24, No Rating 38 |
| Earthquake | 84 of 84 | 21.6 | 75.5 | 87.3 | Relatively Moderate 25, Relatively Low 57, Very Low 2 |
| Hail | 84 of 84 | 5.0 | 23.3 | 42.3 | Relatively Low 2, Very Low 82 |
| Heat Wave | 84 of 84 | 25.5 | 74.8 | 89.6 | Relatively High 6, Relatively Moderate 62, Relatively Low 16 |
| Hurricane | 84 of 84 | 55.3 | 83.2 | 90.2 | Relatively High 2, Relatively Moderate 71, Relatively Low 11 |
| Ice Storm | 84 of 84 | 28.8 | 84.5 | 93.6 | Relatively High 12, Relatively Moderate 66, Relatively Low 5, Very Low 1 |
| Inland Flooding | 84 of 84 | 1.3 | 82.0 | 99.5 | Very High 11, Relatively High 34, Relatively Moderate 28, Relatively Low 9, Very Low 2 |
| Landslide | 78 of 84 | 10.1 | 41.5 | 91.6 | Relatively Low 1, Very Low 77, No Rating 6 |
| Lightning | 84 of 84 | 22.8 | 65.4 | 85.7 | Relatively High 6, Relatively Moderate 60, Relatively Low 18 |
| Strong Wind | 84 of 84 | 58.7 | 95.0 | 99.1 | Very High 19, Relatively High 60, Relatively Moderate 5 |
| Tornado | 84 of 84 | 24.2 | 45.8 | 60.1 | Relatively Moderate 5, Relatively Low 75, Very Low 4 |
| Wildfire | 58 of 84 | 25.1 | 69.9 | 86.6 | Relatively Low 30, Very Low 28, No Rating 26 |
| Winter Weather | 84 of 84 | 54.1 | 87.8 | 95.7 | Relatively High 66, Relatively Moderate 18 |
Drought: Agriculture is all of NRI's expected annual loss for this hazard in the county, so the tract range mostly reflects where crop and livestock value is.
Rated tracts only: No Rating (score 0.0), Not Applicable and Insufficient Data tracts are counted but not used for the minimum, median and maximum.
The score ranks a tract against all U.S. tracts (100 = highest). The rating is FEMA's category for the tract's risk value, computed differently, so the two can disagree.
Frequency data for cold wave, drought, hail, heat wave, ice storm, lightning, strong wind and winter weather are county-wide or coarse (49 km grid or NWS zone), the same for every jurisdiction; the tract range mostly reflects where buildings and people are (crop and livestock value where a line above names agriculture).
Each jurisdiction (starting figures from federal data)
Sources: 1, 3, 4, 6
| Jurisdiction | Type | Plan status | Repetitive lossFMA RL and SRL (44 CFR 77.2); repeat-flood, any definition | Public Assistance to this jurisdictionFEMA records matched by applicant name; federal share obligated, nominal dollars | Event records naming this placeall years; since its plan | Notes |
|---|---|---|---|---|---|---|
| Mercer County | County | Approved, expires 2026-12-09 | $12,430,792.15 | 0 total; 0 since its plan | No NFIP community ID on this jurisdiction's plan row. Includes $5,464,632.50 for declarations not counted as hazard incidents (DR-4488-NJ, EM-3169-NJ). | |
| Hightstown borough | Borough | Approved, expires 2026-12-09 | FMA RL 0, SRL 0; any 1 | $1,291,263.05 | 9 total; 0 since its plan | |
| Hopewell borough | Borough | Approved, expires 2026-12-09 | FMA RL 0, SRL 0; any 1 | $515,599.88 | 25 total; 5 since its plan | |
| Pennington borough | Borough | Approved, expires 2026-12-09 | FMA RL 0, SRL 0; any 1 | $264,756.89 | 16 total; 5 since its plan | |
| Princeton | Borough | Approved, expires 2026-12-09 | FMA RL 1, SRL 1; any 5 | $361,528.53 | 45 total; 2 since its plan | |
| Trenton city | City | Approved, expires 2026-12-09 | FMA RL 1, SRL 18; any 189 | $1,887,591.19 | 37 total; 1 since its plan | |
| East Windsor township | Township | Approved, expires 2026-12-09 | FMA RL 0, SRL 0; any 0 | $1,199,597.25 | 17 total; 2 since its plan | Includes $165,630.01 for declarations not counted as hazard incidents (DR-4488-NJ). |
| Ewing township | Township | Approved, expires 2026-12-09 | FMA RL 0, SRL 5; any 60 | $935,291.57 | 1 total; 0 since its plan | |
| Hamilton township | Township | Approved, expires 2026-12-09 | FMA RL 2, SRL 2; any 18 | $2,154,320.70 | 0 total; 0 since its plan | |
| Hopewell township | Township | Approved, expires 2026-12-09 | FMA RL 2, SRL 4; any 10 | $3,067,952.18 | 25 total; 5 since its plan | |
| Lawrence township | Township | Approved, expires 2026-12-09 | FMA RL 3, SRL 4; any 15 | $1,405,451.50 | 0 total; 0 since its plan | Includes $118,713 for declarations not counted as hazard incidents (DR-4488-NJ). |
| Robbinsville township | Township | Approved, expires 2026-12-09 | FMA RL 0, SRL 0; any 0 | $560,762.67 | 7 total; 0 since its plan | Includes $108,332 for declarations not counted as hazard incidents (DR-4488-NJ). |
| West Windsor township | Township | Approved, expires 2026-12-09 | FMA RL 1, SRL 2; any 13 | $1,030,475.71 | 0 total; 0 since its plan |
Repetitive-loss counts are for whole NFIP communities, which can extend beyond this county (see the note in B2-c).
County Public Assistance in B1-d also includes applicants filed under the county that are not jurisdictions in this plan (for example state agencies, special districts and nonprofits), so the jurisdiction rows add up to less.
Supports FEMA checklist items B2-a and B2-b: vulnerability and potential impacts
Local data needed
The table below gives county-level starting figures; the plan describes impacts for each jurisdiction and its own assets.
- Critical facilities and lifelines per hazard
- A problem statement per jurisdiction per hazard
- Changes in development in hazard-prone areas since the last approval, or a statement of none (E1-a)
- Future assets
County-level starter: exposure, expected annual loss and damage since the plan
Sources: 1, 2, 3, 5, 6, 7
| Hazard | Building exposuremodeled dollars | Agriculture exposuremodeled dollars | Population exposedpeople | EAL buildingsmodeled dollars per year | EAL agriculturemodeled dollars per year | Cost of expected deaths and injuriesFEMA's dollar value per year, not property damage | EAL as % of exposurebuildings; agriculture where noted | Storm Events damage since 2021-12-10county-coded records, property plus crops, nominal dollars | Zone-level damage since planproperty plus crops, reported for the zone | Public Assistance since plannominal dollars; see note | Note |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Coastal Flooding | $203,655,464 | n/a | 879 | $326,656 | n/a | $2,579 | 0.16% | $0 | |||
| Cold Wave | $92,572,190,968 | $32,164,885 | 386,483 | $262 | $8 | $4,831,864 | under 0.0001% | $0 | |||
| Drought | n/a | $24,468,512 | n/a | n/a | $304,640 | n/a | 1.25% (agriculture) | NRI has no building exposure for this hazard; agriculture shown | |||
| Earthquake | $162,997,147,169 | n/a | 387,340 | $7,429,144 | n/a | $3,164,505 | 0.00456% | ||||
| Hail | $92,572,190,968 | $32,164,885 | 386,483 | $49,694 | $23,289 | $37,234 | under 0.0001% | $0 | |||
| Heat Wave | $92,572,190,968 | $32,164,885 | 386,483 | under $1 | $98 | $6,829,255 | under 0.0001% | $0 | |||
| Hurricane | $92,534,591,890 | $32,164,885 | 386,014 | $17,435,955 | $151,772 | $539,576 | 0.0188% | ||||
| Ice Storm | $92,437,756,916 | n/a | 385,709 | $1,665,845 | n/a | $190,470 | 0.0018% | ||||
| Inland Flooding | $92,522,921,124 | $1,214,641 | 9,288 | $108,143,494 | $47,171 | $5,366,973 | n/a (see note) | $40,000 | NRI counts the full building value of any census block with some flood loss; this is not the value of buildings in the floodplain. Use local FIRM overlays for B2-a/B2-b. | ||
| Landslide | $445,305,635 | n/a | 1,461 | $1,593 | n/a | $15 | 0.000358% | ||||
| Lightning | $92,572,190,968 | n/a | 386,483 | $109,268 | n/a | $1,361,277 | 0.000118% | ||||
| Strong Wind | $92,572,190,968 | $32,164,885 | 386,483 | $9,120,944 | $5,011 | $3,605,573 | 0.00985% | $10,000 | |||
| Tornado | $92,572,190,968 | $32,164,885 | 386,483 | $1,856,319 | $274 | $2,247,990 | 0.00201% | $0 | |||
| Wildfire | $3,419,230,614 | $6,457,727 | 27,282 | $187,717 | $28 | $28,181 | 0.00549% | ||||
| Winter Weather | $92,572,190,968 | $32,164,885 | 386,483 | $208,144 | $10 | $929,074 | 0.000225% | $0 |
Totals since 2021-12-10 (Storm Events through 2026-06-30): 62 county-coded records, 23 with a damage value recorded (including $0), $50,000; 36 zone-level records, 29 with a damage value recorded (including $0), $0 reported for the zone; Public Assistance: no counted declaration since the plan.
FEMA does not split Public Assistance by hazard. A declaration mapped to several hazards is listed under each of them with its full amount, so the per-hazard column does not add up to the total; the unit total counts each declaration once.
NRI computes earthquake exposure on its own basis, so it exceeds the county building value in B2-a.
Supports FEMA checklist item B2-a: vulnerability (county context)
County context
Source: 5
| Measure | Value |
|---|---|
| Population | 386,483 |
| Building value (total, not at risk) | $92,572,190,968 |
| Agriculture value (total, not at risk) | $32,164,885 |
| NRI risk rating (all hazards) | Relatively High |
| Expected annual loss, buildings and agriculture, all hazards | $147,067,337 |
| Expected annual loss, population equivalence, all hazards (NRI values each statistical life at $13.7M; a modeled value of expected deaths and injuries, not property damage) | $29,134,566 |
| Social vulnerability rating | Relatively Moderate |
| Community resilience rating | Relatively High |
| NRI version | December 2025 |
FEMA's all-hazard expected annual loss adds buildings, agriculture and population equivalence; this table gives the property part and the population-equivalence part as separate rows.
Social vulnerability: higher means people are more likely to be harmed and slower to recover. Community resilience: lower means the community is less able to recover. High social vulnerability and low resilience both raise the NRI risk rating.
Supports FEMA checklist item B2-c: repetitive loss properties
Repetitive loss in this county, both definitions
Sources: 1, 4
| Definition | Properties | Severe repetitive loss | Properties |
|---|---|---|---|
| Repetitive loss, FMA definition (44 CFR 77.2) | 10 | Severe repetitive loss, FMA definition (44 CFR 77.2) | 36 |
| Repetitive loss, NFIP insurance definition | 307 | Severe repetitive loss, NFIP insurance definition | 33 |
The state NFIP coordinator's list, the source FEMA's Handbook names, often uses the NFIP insurance definition (second row).
Repeat-flood properties: county and state-level rows
Sources: 1, 4
| Scope | RL, FMAproperties | SRL, FMAproperties | RL, NFIPproperties | SRL, NFIPproperties | Any categoryproperties | Mitigatedproperties | Currently insuredproperties |
|---|---|---|---|---|---|---|---|
| County total | 10 | 36 | 307 | 33 | 313 | 2 | 119 |
| of which: Hamilton township | 2 | 2 | 17 | 2 | 18 | 0 | 7 |
| of which: Hightstown borough | 0 | 0 | 1 | 0 | 1 | 0 | 1 |
| of which: Hopewell borough | 0 | 0 | 1 | 0 | 1 | 0 | 1 |
| of which: Lawrence township | 3 | 4 | 13 | 3 | 15 | 0 | 5 |
| of which: Pennington borough | 0 | 0 | 1 | 0 | 1 | 0 | 0 |
| of which: Princeton borough | 1 | 1 | 4 | 1 | 5 | 0 | 1 |
| of which: West Windsor township | 1 | 2 | 13 | 2 | 13 | 0 | 3 |
| of which: Ewing township | 0 | 5 | 59 | 4 | 60 | 1 | 18 |
| of which: Hopewell township | 2 | 4 | 10 | 4 | 10 | 0 | 3 |
| of which: Trenton city | 1 | 18 | 188 | 17 | 189 | 1 | 80 |
| Statewide, no county in FEMA's file | 0 | 1 | 5 | 0 | 6 | 1 | 0 |
The statewide row counts properties FEMA's file gives with no county in this state; they are listed for reference and are not in this county's counts.
Repeat-flood properties by jurisdiction in the plan (NFIP community)
Sources: 1, 4
| Jurisdiction | NFIP community ID | RL, FMAproperties | SRL, FMAproperties | RL, NFIPproperties | SRL, NFIPproperties | Any categoryproperties | Mitigatedproperties | Currently insuredproperties |
|---|---|---|---|---|---|---|---|---|
| Hightstown borough | 340247 | 0 | 0 | 1 | 0 | 1 | 0 | 1 |
| Hopewell borough | 340248 | 0 | 0 | 1 | 0 | 1 | 0 | 1 |
| Pennington borough | 340251 | 0 | 0 | 1 | 0 | 1 | 0 | 0 |
| Princeton | 340252 | 1 | 1 | 4 | 1 | 5 | 0 | 1 |
| Trenton city | 345325 | 1 | 18 | 188 | 17 | 189 | 1 | 80 |
| East Windsor township | 340244 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Ewing township | 345294 | 0 | 5 | 59 | 4 | 60 | 1 | 18 |
| Hamilton township | 340246 | 2 | 2 | 17 | 2 | 18 | 0 | 7 |
| Hopewell township | 345298 | 2 | 4 | 10 | 4 | 10 | 0 | 3 |
| Lawrence township | 340250 | 3 | 4 | 13 | 3 | 15 | 0 | 5 |
| Robbinsville township | 340255 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| West Windsor township | 340256 | 1 | 2 | 13 | 2 | 13 | 0 | 3 |
Counts by occupancy group for each jurisdiction are in the Excel file, sheet "B2-c Jurisdictions".
Jurisdiction rows are whole NFIP communities and need not add up to the county total: a community that extends into another county is counted in full on each jurisdiction row, while the county table counts only its part in this county.
County repeat-flood properties by occupancy group
Sources: 1, 4
| Occupancy group | RL, FMAproperties | SRL, FMAproperties | RL, NFIPproperties | SRL, NFIPproperties | Any categoryproperties | Mitigatedproperties | Currently insuredproperties |
|---|---|---|---|---|---|---|---|
| single-family residential | 8 | 21 | 251 | 20 | 256 | 1 | 109 |
| 2 to 4 unit residential | 0 | 3 | 17 | 3 | 17 | 0 | 4 |
| other residential | 0 | 0 | 2 | 0 | 2 | 0 | 0 |
| non-residential | 2 | 12 | 37 | 10 | 38 | 1 | 6 |
| not reported | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
FEMA's occupancy groups have no institutional class; institutional properties are counted in non-residential or other residential in the table by occupancy group.
FMA RL and FMA SRL are the Flood Mitigation Assistance definitions (44 CFR 77.2), the ones the FEMA Local Mitigation Planning Policy Guide cites. NFIP repetitive loss (the FEMA insurance definition) is 2 or more claims over $1,000 in 10 years, and a property can leave that group once it is mitigated. Also shown: NFIP severe repetitive loss, any category, mitigated and currently insured. The Methods page gives the OpenFEMA field details.
Counts are aggregates of FEMA's public NFIP Multiple Loss Properties file (FEMA's data date 2026-08-02; file version 2026-08-04). No property is identified. County assignment is FEMA's geocode.
In this county 3 properties are FMA repetitive loss but not NFIP repetitive loss, and 300 properties are NFIP repetitive loss but not FMA repetitive loss.
Exact counts; no count suppression.
Sources
Tables cite these sources by number. The full list, for the plan's bibliography (FEMA review item A4-a):
- FEMA, OpenFEMA HazardMitigationPlanStatuses v1, version 2026-09-29T134039Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/HazardMitigationPlanStatuses (API)
- FEMA, OpenFEMA DisasterDeclarationsSummaries v2, version 2026-09-29T162832Z, pulled 2026-09-30, https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries (API)
- FEMA, OpenFEMA PublicAssistanceFundedProjectsSummaries v1, version 2026-09-29T150754Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/PublicAssistanceFundedProjectsSummaries (API)
- FEMA, OpenFEMA NfipMultipleLossProperties v1, version 2026-08-04T164045Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/NfipMultipleLossProperties (API)
- FEMA, FEMA National Risk Index 1.20.0 (December 2025), county and census tract tables, version 1.20.0, pulled 2026-09-30, https://www.fema.gov/about/reports-and-data/openfema/nri/v120/NRI_Table_Counties.zip (download, 25 MB), https://www.fema.gov/about/reports-and-data/openfema/nri/v120/NRI_Table_CensusTracts.zip (download, 635 MB)
- NOAA NCEI, NOAA NCEI Storm Events Database, details files (csvfiles v1.0), version c20260918, pulled 2026-09-30, https://www.ncei.noaa.gov/pub/data/swdi/stormevents/csvfiles/
- NOAA National Weather Service, NWS county-public forecast zones correlation file, version bp03mr20 to bp16ap26 (11 files; newest bp16ap26), pulled 2026-09-30, https://www.weather.gov/gis/ZoneCounty
- U.S. Census Bureau, Census 2024 Gazetteer, 2020 place by county, CT county-to-cousub crosswalk, version 2024-gazetteer, pulled 2026-09-30, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_counties_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_cousubs_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_place_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_unsd_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_elsd_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_scsd_national.zip, https://www2.census.gov/geo/docs/reference/codes2020/national_place_by_county2020.txt, https://www2.census.gov/geo/docs/reference/ct_change/ct_cou_to_cousub_crosswalk.xlsx (used to match place names and codes; no table prints its values)
What this packet is and what the plan adds
This packet is the federal data for the plan's risk assessment (the summary on page 1 says how it is organized); the plan and FEMA's review decide whether each item is met.
The plan adds what only the community has: local data on assets, critical facilities, development and each jurisdiction's impacts; local hazard history, including state-declared emergencies; the mitigation strategy; and adoption.
How the federal data are built: National Risk Index values are FEMA's model, not counts of events. Storm Events is more complete from 1996; zone-level records are placed by forecast zone, not by location in the county. Public Assistance for a jurisdiction is matched by applicant name. The Methods page gives every rule and the known edge cases.
OpenFEMA disclaimer
This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Reuse, citation and corrections
Reuse and citation: Hazard Plain text and tables are licensed under Creative Commons Attribution 4.0 International (CC BY 4.0, https://creativecommons.org/licenses/by/4.0/); credit Hazard Plain and the release. The underlying federal data are public domain; OpenFEMA data are also subject to the OpenFEMA terms and conditions.
Cite this: Hazard Plain (2026). Mercer County, NJ: risk-assessment baseline packet, release 2026-10 (data as of 2026-09-30; County FIPS 34021). Automated baseline. https://hazardplain.org/nj/34021/ Built from FEMA OpenFEMA, the FEMA National Risk Index and NOAA NCEI Storm Events; source versions in the packet's Sources list.
Corrections: to report an error, name the packet, the table and what your records show. Contact: [email protected]