Hazard Plain Automated baseline

Rock County, WI

Risk-assessment baseline packet

County FIPS:
55105
Release:
2026-10
Data as of:
2026-09-30
Storm Events data through:
2026-06-30

Hazard Plain is an independent product built from public federal data. It is not a FEMA document and is not reviewed or endorsed by FEMA or any state agency.

Hazard Plain release 2026-10, as of 2026-09-30.

Summary

Plan status as of 2026-09-30: Approved, expires 2028-04-19. Plan: Rock County (FEMA plan 109006), approved 2023-04-20.

Since the plan was approved on 2023-04-20: 1 new hazard declaration (1 incident) and 135 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 ($37,904,274 a year), Tornado ($12,938,166) and Cold Wave ($12,583,621).

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 2028-04-19
Plan:
Rock County (FEMA plan 109006)
Approved:
2023-04-20
Days to expiry:
567

What changed since your last plan (approved 2023-04-20)

New federal declarations:
1 new hazard declaration (1 incident): DR-4923-WI (Severe Storms, Tornadoes, and Flooding)
Storm Events records since approval:
135 records (data through 2026-06-30)
Repetitive loss now:
FMA RL 1, SRL 1 (44 CFR 77.2); any definition: 14
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: 15 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

JurisdictionTypeStatusPlanApprovedExpiresDays to expirynegative = days since expiryUpdate underwayNotes
Rock CountyCountyApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567
Beloit cityCityApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-06-01
Brodhead cityCityPlan 108643 approved 2023-04-04, pending adoption here; not yet eligibleGreen County Hazard Mitigation Plan (FEMA plan 108643), pending adoption here2023-04-04 by FEMA; not yet adopted here2028-04-03 once adoptedFEMA tracker shows a plan approvable pending adoptionNot yet eligible: adopt the approved plan.
Clinton villageVillagePlan 109006 approved 2023-04-20, pending adoption here; not yet eligibleRock County (FEMA plan 109006), pending adoption here2023-04-20 by FEMA; not yet adopted here2028-04-19 once adoptedFEMA tracker shows a plan approvable pending adoptionNot yet eligible: adopt the approved plan.
Edgerton cityCityApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567Also approved under plan 108424 (Dane County, expires 2027-12-06). FEMA's plan status map shows one plan per jurisdiction and may show one of these; this packet uses the approved plan that expires last. this jurisdiction approved 2024-06-01
Evansville cityCityApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-06-01
Footville villageVillageApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-05-31
Janesville cityCityPlan 109006 approved 2023-04-20, pending adoption here; not yet eligibleRock County (FEMA plan 109006), pending adoption here2023-04-20 by FEMA; not yet adopted here2028-04-19 once adoptedFEMA tracker shows a plan approvable pending adoptionNot yet eligible: adopt the approved plan.
Milton cityCityApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-06-01
Orfordville villageVillageApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-05-31
Harmony townTownApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-06-01
La Prairie townTownApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-05-31
Milton townTownApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-05-31
Plymouth townTownApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-05-31
Spring Valley townTownApproved, expires 2028-04-19Rock County (FEMA plan 109006)2023-04-202028-04-19567this jurisdiction approved 2024-05-31

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 EALHazardNRI risk ratingEAL ratingEAL buildingsmodeled dollars per yearEAL agriculturemodeled dollars per yearCost of expected deaths and injuriesFEMA's dollar value per year, not property damageEAL total (see note)modeled dollars per yearStorm Events records, 1996 to 2026-06-30countStorm Events coverage note
1Inland FloodingRelatively ModerateRelatively Moderate$37,556,698$323,975$23,602$37,904,27490
2TornadoRelatively HighRelatively High$6,220,713$1,431$6,716,021$12,938,16622
3Cold WaveRelatively HighRelatively High$176$2,375$12,581,070$12,583,62139
4HailRelatively HighRelatively High$3,578,000$156,891$196,106$3,930,996153
5Strong WindRelatively HighRelatively High$843,988$123,134$1,046,000$2,013,122344Includes 17 High Wind and 41 Strong Wind records (NOAA non-thunderstorm wind types, outside NRI's Strong Wind definition).
6Heat WaveRelatively ModerateRelatively Moderate$518$4$1,910,181$1,910,70352
7LightningRelatively HighRelatively High$317,335n/a$782,857$1,100,19238
8EarthquakeVery LowRelatively Low$429,541n/a$99,002$528,543Storm Events does not record earthquakes.
9DroughtRelatively LowRelatively Lown/a$151,897n/a$151,89717
10Ice StormRelatively LowRelatively Moderate$24,305n/a$122,694$146,9995
11Winter WeatherRelatively ModerateRelatively Moderate$2,057$1,755$110,501$114,313223
12WildfireVery LowVery Low$12,686$34$1,669$14,3890No recorded events in Storm Events since 1996 (data through 2026-06-30).
13HurricaneVery LowVery Low$2,736$1,745under $1$4,4810No recorded events in Storm Events since 1996 (data through 2026-06-30).
14LandslideVery LowVery Low$606n/a$2,673$3,2790No 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 wildfire and landslide records (Storm Events records these hazards only in part).

Not applicable to this county per NRI, with no federal declaration and no Storm Events record since 1996: avalanche, coastal flooding, 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.

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

HazardHighest-rated census tractsNRI risk rating, score 0 to 100
Earthquaketract 14 (Relatively Low, 56.0); tract 10 (Relatively Low, 55.2); tract 26.01 (Relatively Low, 46.4)
Hurricanetract 32 (Very Low, 27.8); tract 27 (Very Low, 27.3); tract 28 (Very Low, 27.2)
Landslidetract 30.02 (Relatively Low, 91.6); tract 12.02 (Relatively Low, 90.7); tract 28 (Relatively Low, 86.9)
Tornadotract 14 (Very High, 95.3); tract 26.01 (Relatively High, 93.0); tract 12.02 (Relatively High, 93.0)
Wildfiretract 30.02 (Relatively Low, 71.7); tract 12.02 (Relatively Low, 71.7); tract 27 (Relatively Low, 71.0)

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 14 is Census Tract 14). 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

HazardScaleRecordscount and yearsObserved rangeWorst recorded eventMost damaging (when different)How it applies to jurisdictionsNote
Cold/Wind Chill, Extreme Cold/Wind Chillwind chill39 records, 1996 to 2026 (39 zone-level)1 day to 13 days (median 2 days); 32 with a recorded value13 consecutive days, 2017-12-25 to 2018-01-06, zone-levelCold/Wind Chill, 2007-02-03, $2,000 property; $0 crops (zone total, 2007 dollars)Countywide (zone-level records).
Frost/Freeze (outside NRI's Cold Wave definition)crop damage0
DroughtU.S. Drought Monitor scale (D0 to D4)17 records, 2002 to 2012 (17 zone-level)11 days to 158 days (median 142 days); 4 with a recorded value158 days (about 5.2 months), 2012-06-26 to 2012-11-30, a run of 6 consecutive Storm Events drought records, zone-levelDrought, 2002-08-01, property not reported; $500,000 crops (zone total, 2002 dollars)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.
EarthquakeModified Mercalli (local data)0Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hailhail size (inches)174 records, 1961 to 20260.75 in to 3 in (median 1 in); 174 with a recorded value3 in hail, 1975-06-04Hail, 2006-04-13, $4,360,000 property; crops not reported (2006 dollars)Event records naming jurisdictions in the plan: Milton city (23 records), Milton town (23 records), Beloit city (18 records), Janesville city (14 records), Evansville city (13 records), Edgerton city (10 records), Orfordville village (10 records), Clinton village (4 records), Footville village (3 records).
Excessive Heat, Heatheat index (in event narratives)52 records, 1998 to 2026 (52 zone-level)1 day to 5 days (median 2 days); 39 with a recorded value5 consecutive days, 2012-07-02 to 2012-07-06, zone-levelCountywide (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 DepressionSaffir-Simpson0Storm 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 StormSperry-Piltz ice scale (local data)5 records, 1997 to 2023 (5 zone-level)Ice Storm, 2008-02-17, $20,000 property; $0 crops (2008 dollars); NWS zone WIZ069Countywide (zone-level records).
Flash Flood, Flood, Lakeshore Flooddamage and flood days (flood depth: FIRM)90 records, 1996 to 2026 (7 zone-level)Flash Flood, 2026-04-17, $30,000,000 property; $0 crops (2026 dollars)Event records naming jurisdictions in the plan: Beloit city (13 records), Janesville city (6 records), Clinton village (5 records), Evansville city (3 records), Milton city (3 records), Milton town (3 records), Orfordville village (3 records), Edgerton city (2 records). Zone-level records (7) 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 Flownone (count and damage only)0
Lightningannualized frequency (the measure FEMA's Local Mitigation Planning Handbook names)38 records, 1996 to 2022Lightning, 2014-06-30, $0 property; $0 crops (2014 dollars), 1 direct deathLightning, 1998-08-24, $3,500,000 property; crops not reported (1998 dollars)Event records naming jurisdictions in the plan: Janesville city (12 records), Beloit city (7 records), Orfordville village (5 records), Edgerton city (2 records), Milton city (2 records), Milton town (2 records), Clinton village (1 record), Evansville city (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)58 records, 1997 to 2026 (56 zone-level)26 kt (30 mph) to 56 kt (64 mph) (median 39 kt (45 mph)); 49 with a recorded value56 kt (64 mph) measured gust, High Wind, 2003-11-12; same speed and measurement basis also recorded on 2001-10-25; NWS zone WIZ069High Wind, 1998-11-10, $600,000 property; $100,000 crops (zone total, 1998 dollars)Event records naming jurisdictions in the plan: Beloit city (1 record), Janesville city (1 record). Zone-level records (56) apply countywide.
Thunderstorm Windwind speed (kt and mph)381 records, 1955 to 202650 kt (58 mph) to 100 kt (115 mph) (median 56 kt (64 mph)); 258 with a recorded value100 kt (115 mph) estimated, Thunderstorm Wind, 2000-08-05, 2 direct injuriesEvent records naming jurisdictions in the plan: Beloit city (48 records), Evansville city (39 records), Janesville city (31 records), Milton city (29 records), Milton town (29 records), Orfordville village (24 records), Clinton village (20 records), Edgerton city (16 records), Footville village (5 records).
TornadoEnhanced Fujita (Fujita before Feb 2007)38 records, 1955 to 2026F/EF0 to F/EF2 (median F/EF1); 37 with a recorded valueEF2 tornado, 2024-02-08, 13.71 mi within this county, 750 yd wide, $6,800,000 property; $0 crops (2024 dollars), 1 direct injuryTornado, 2024-06-22, $24,800,000 property; crops not reported (2024 dollars)Event records naming jurisdictions in the plan: Evansville city (3 records), Milton city (2 records), Milton town (2 records), Beloit city (1 record), Clinton village (1 record).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).
Wildfireacres burned (local data)0
Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleetnone in data (snowfall: local data)223 records, 1996 to 2026 (223 zone-level)Winter Storm, 2024-01-12, $20,000 property; $0 crops (2024 dollars); NWS zone WIZ069Countywide (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: 16 declarations covering 13 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

DeclaredIncident beganFEMA numberTypeTitleMapped hazardCounty Public Assistancefederal share obligated, nominal dollarsFlagsNotes
2026-06-302026-04-13DR-4923-WIMajor disasterSevere Storms, Tornadoes, and FloodingInland Flooding (primary); also designated: Tornado$238,030.72new since last plan; within last 5 years
2020-04-042020-01-20DR-4520-WIMajor disasterCOVID-19 PandemicNon-natural, not counted$636,768.89
2020-03-132020-01-20EM-3454-WIEmergencyCOVID-19Non-natural, not countedno Public Assistance recordedsame incident as DR-4520
2008-06-142008-06-05DR-1768-WIMajor disasterSevere Storms, Tornadoes, and FloodingInland Flooding; Tornado$1,696,693.84
2008-03-192008-02-05EM-3285-WIEmergencyRecord Snow and Near Record SnowWinter Weather$337,899.62
2007-08-262007-08-18DR-1719-WIMajor disasterSevere Storms and FloodingInland FloodingPA not declared for this county
2005-09-132005-08-29EM-3249-WIEmergencyHurricane Katrina EvacuationHurricane: evacuation support, not a local hazard event; not countedno Public Assistance recorded
2004-06-182004-05-07DR-1526-WIMajor disasterSevere Storms and FloodingInland FloodingPA not declared for this county
2001-01-242000-12-11EM-3163-WIEmergencySnowWinter Weather$178,169.83
1998-08-121998-08-05DR-1238-WIMajor disasterSevere Storms and FloodingInland Flooding; Winter Weatherno Public Assistance recorded
1993-07-021993-06-07DR-994-WIMajor disasterSevere Storms, Tornadoes & FloodingInland Flooding; Tornadono Public Assistance recorded
1990-07-131990-06-22DR-874-WIMajor disasterSevere Storms, Tornadoes & FloodingInland Flooding; Tornadono Public Assistance recorded
1978-07-071978-07-07DR-559-WIMajor disasterSevere Storms, Flooding, Hail & TornadoesHail; Inland Flooding; Tornadono Public Assistance recorded
1976-06-171976-06-17EM-3014-WIEmergencyDroughtDroughtno Public Assistance recorded
1976-03-231976-03-23DR-496-WIMajor disasterSevere Storms, Icing, Wind & FloodingInland Floodingno Public Assistance recorded
1973-04-271973-04-27DR-376-WIMajor disasterSevere Storms & FloodingInland Floodingno 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.

Public Assistance filed under this county for declarations that do not list it: 2 rows, $5,694.29

Sources: 2, 3

FEMA numberDeclaredTitleApplicantPA obligatedfederal share obligated, nominal dollars
DR-1966-WI2011-04-05Severe Winter Storm and SnowstormBlackhawk Technical College$907.50
DR-1966-WI2011-04-05Severe Winter Storm and SnowstormAlbion, Town of (Dane County)$4,786.79

FEMA's Public Assistance summaries file these applicants under this county, but FEMA's declaration rows for these disasters do not designate it (an electric cooperative or district serving several counties, for example). Not in any declaration row above and not counted.

Public Assistance not placed in any Wisconsin county: 1 row, $87,788.41; listed on the Wisconsin state page.

Source: 3

Previous occurrences by hazard, with explicit no-event rows

Sources: 2, 6, 7

HazardStorm Events records, all years on file(years in the Period column)Since plan approvalrecordsIn the 12 months before plan approvalrecordsLast 5 yearsrecordsDeclared incidents, all yearsseparate disastersDeclared since approvalseparate disastersPeriodStatement
Cold Wave39415001996 to 2026-06-30
Drought17000101996 to 2026-06-30
Earthquake000000Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hail174381149101955 to 2026-06-30
Heat Wave52639001996 to 2026-06-30
Hurricane0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Ice Storm5011001996 to 2026-06-30
Inland Flooding90160161011996 to 2026-06-30
Landslide0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Lightning38011001996 to 2026-06-30
Strong Wind43938849001955 to 2026-06-30Includes 17 High Wind and 41 Strong Wind records.
Tornado389312511950 to 2026-06-30
Wildfire0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Winter Weather22324945301996 to 2026-06-30

Notable Storm Events records

Sources: 1, 6, 7

DateEvent typeMagnitude or extentDamagenominal dollarsDeaths, injuriesdirect onlyLocationFlagsWhy listed
2026-04-17Flash Flood$30,000,000 property; $0 crops (2026 dollars)0, 0DOWNTOWN JANESVILLE to LEYDENnew since last plan; within last 5 yearsB1-c worst recorded: Flash Flood, Flood, Lakeshore Flood
2024-02-08TornadoEF2, 13.71 mi within this county, 750 yd wide$6,800,000 property; $0 crops (2024 dollars)0, 1MAGNOLIA to EDGERTON ALBION ARPTnew since last plan; within last 5 yearsB1-c worst recorded: Tornado
2018-01-17Cold/Wind Chill$0 property; $0 crops (zone total, 2018 dollars)1, 0NWS zone WIZ069 (ROCK), zone-leveldeaths or injuries recorded
2017-12-25Cold/Wind Chillproperty not reported; $0 crops (zone total, 2017 dollars)0, 0NWS zone WIZ069 (ROCK), zone-levelB1-c worst recorded: Cold/Wind Chill, Extreme Cold/Wind Chill
2014-06-30Lightning$0 property; $0 crops (2014 dollars)1, 0DOWNTOWN JANESVILLEdeaths or injuries recorded
2014-02-20High Wind37 kt (43 mph) measured sustainedproperty not reported; $0 crops (zone total, 2014 dollars)1, 0NWS zone WIZ069 (ROCK), zone-leveldeaths or injuries recorded
2012-07-02Excessive Heatdamage not reported0, 0NWS zone WIZ069 (ROCK), zone-levelB1-c worst recorded: Excessive Heat, Heat
2012-06-26Drought$0 property; $0 crops (zone total, 2012 dollars)0, 0NWS zone WIZ069 (ROCK), zone-levelB1-c worst recorded: Drought
2008-02-17Ice Storm$20,000 property; $0 crops (zone total, 2008 dollars)0, 0NWS zone WIZ069 (ROCK), zone-levelB1-c worst recorded: Ice Storm
2003-11-12High Wind56 kt (64 mph) measured gust$4,000 property; crops not reported (zone total, 2003 dollars)0, 0NWS zone WIZ069 (ROCK), zone-levelB1-c worst recorded: High Wind and Strong Wind
2000-08-05Thunderstorm Wind100 kt (115 mph) estimated$5,000,000 property; $1,250,000 crops (2000 dollars)0, 2EVANSVILLEB1-c worst recorded: Thunderstorm Wind
1975-06-04Hail3 indamage not recorded (pre-1996 record)0, 0location not recordedB1-c worst recorded: Hail

The full list is in the Excel file, sheet "B1-d Storm Events history" (1,115 rows).

Location is the place NOAA recorded, as written in its data; it need not be a jurisdiction in this plan.

1 Fire Management declaration (1980-04-24 to 1980-04-24) FEMA filed as Statewide with no county; each names one local fire. Listed on the state page.

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

HazardFEMA annualized frequency (modeled)unit per rowUnitIn plain termsDescriptorDescriptor basisNRI events or days in its record period (hail, wind and tornado are area-weighted, so can be fractional)NRI periodLocationNote
Cold Wave5.37event-days per yearabout 5.37 days per yearLikelyStorm Events event-days in 20 of 30 years, 1996 to 2025 (66.7%)1022005-11-12 to 2024-11-12 (19 years)countywide
Drought6.6event-days per yearabout 6.6 days per yearLikelyStorm Events event-days in 4 of 30 years, 1996 to 2025 (13.3%)2592000 to 2025 (25.25 years; D3 and D4 only)countywide
Earthquake0.000891annual probability at a locationchance a given location in the county has at least minor-damage shaking in a year: 0.0891%not shownmodeledsee B1-fNo descriptor (Storm Events does not record earthquakes).
Hail4.34events per yearabout 4.34 per yearHighly likelyFEMA annualized frequency (modeled)164.9 (modeled)1986 to 2023 (38 years)countywide
Heat Wave3.63event-days per yearabout 3.63 days per yearLikelyStorm Events event-days in 19 of 30 years, 1996 to 2025 (63.3%)532005-11-12 to 2024-11-12 (19 years)countywide
Hurricane0.00575events per yearabout 1 in 174 yearsUnlikelyFEMA annualized frequency (modeled)21851 to 2024 (Atlantic)see B1-fNRI counts hurricane and tropical storm tracks passing within storm-force wind range; federal declarations are in B1-d.
Ice Storm0.633event-days per yearabout 0.633 days per yearLikelyStorm Events event-days in 5 of 30 years, 1996 to 2025 (16.7%)431946-12-31 to 2014-02-12 (67 years)countywide
Inland Flooding2.11event-days per yearabout 2.11 days per yearLikelyStorm Events event-days in 22 of 30 years, 1996 to 2025 (73.3%)591996 to 2023 (28 years)see B1-f
Landslide0.133events per year (modeled)about 1 in 8 yearsLikelyFEMA annualized frequency (modeled)not shownmodeledsee B1-f
Lightning38.5days per year with a strikeabout 38.5 days per yearHighly likelyFEMA annualized frequency (modeled)not shown1995 to 2023 (29 years; CONUS)countywide
Strong Wind5.46events per yearabout 5.46 per yearHighly likelyFEMA annualized frequency (modeled)2081986 to 2023 (38 years)countywide
Tornado0.579events per yearabout 0.58 per yearLikelyFEMA annualized frequency (modeled)not shown1950 to 2023 (EF2+); 1986 to 2023 (EF0-1)see B1-f
Wildfire0.000104annual probability at a locationchance a given location in the county burns in a year: 0.0104%Storm Events records in 0 of 30 years, 1996 to 2025 (0%)not shownmodeledsee B1-fNo descriptor: no Storm Events record 1996 to 2025
Winter Weather14.1event-days per yearabout 14.1 days per yearHighly likelyStorm Events event-days in 29 of 30 years, 1996 to 2025 (96.7%)2672005-11-12 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

UnitDescriptorDefinition
events per yearHighly likely1 or more per year
events per yearLikelyabout once in 1 to 10 years
events per yearPossibleabout once in 10 to 100 years
events per yearUnlikelyless than once in 100 years
annual probabilityLikely10% to under 100% chance in a given year
annual probabilityPossible1% to under 10% chance in a given year
annual probabilityUnlikelyunder 1% chance in a given year
event-days (share of years)Highly likelyevent-days recorded in 90% or more of years
event-days (share of years)Likelyevent-days recorded in 10% to under 90% of years
event-days (share of years)Possibleevent-days recorded in some years but under 10% of years
lightning strike-daysHighly likelycloud-to-ground strikes on 1 or more days per year

Intensity bands: historical frequency (Storm Events)

Source: 6

HazardBandYearsEventscounty-coded recordsYears in periodEvents per yearevents / years
Hail1.00-1.99 in1996 to 202580302.67
Hail2.00 in+1996 to 202512300.4
Thunderstorm Wind (counted as NRI Strong Wind)50-64 kt1996 to 2025180306
Thunderstorm Wind (counted as NRI Strong Wind)65 kt+1996 to 202546301.53
Thunderstorm Wind (counted as NRI Strong Wind)unmeasured or below 50 kt1996 to 202554301.8
TornadoEF0-11996 to 202516300.533
TornadoEF2-31996 to 20253300.1
TornadoEF4-51996 to 20250300
Tornadounrated (EFU)1996 to 20250300

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

HazardTractsrated of allNRI risk score, 0 to 100Tracts by rating
MinMedianMax
Cold Wave41 of 4160.587.995.3Very High 2, Relatively High 35, Relatively Moderate 4
Drought30 of 4167.079.391.6Relatively Low 16, Very Low 14, No Rating 11
Earthquake41 of 419.627.256.0Relatively Low 5, Very Low 36
Hail41 of 4172.688.996.0Relatively High 22, Relatively Moderate 19
Heat Wave41 of 4115.851.871.5Relatively Moderate 18, Relatively Low 22, Very Low 1
Hurricane41 of 4113.718.327.8Very Low 41
Ice Storm41 of 419.939.457.6Relatively Low 28, Very Low 13
Inland Flooding41 of 4121.054.995.9Very High 1, Relatively High 11, Relatively Moderate 15, Relatively Low 14
Landslide40 of 4114.354.891.6Relatively Low 6, Very Low 34, No Rating 1
Lightning41 of 4135.773.488.7Relatively High 16, Relatively Moderate 24, Relatively Low 1
Strong Wind41 of 4139.377.389.1Relatively High 9, Relatively Moderate 30, Relatively Low 2
Tornado41 of 4155.983.195.3Very High 1, Relatively High 30, Relatively Moderate 10
Wildfire39 of 4118.541.671.7Relatively Low 3, Very Low 36, No Rating 2
Winter Weather41 of 4127.350.362.8Relatively Moderate 22, Relatively Low 19

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

JurisdictionTypePlan statusRepetitive lossFMA RL and SRL (44 CFR 77.2); repeat-flood, any definitionPublic Assistance to this jurisdictionFEMA records matched by applicant name; federal share obligated, nominal dollarsEvent records naming this placeall years; since its planNotes
Rock CountyCountyApproved, expires 2028-04-19FMA RL 1, SRL 0; any 9$638,497.480 total; 0 since its planIncludes $618,111.92 for declarations not counted as hazard incidents (DR-4520-WI).
Beloit cityCityApproved, expires 2028-04-19FMA RL 0, SRL 0; any 2$407,263.0488 total; 6 since its plan
Brodhead cityCityPlan 108643 approved 2023-04-04, pending adoption here; not yet eligibleFMA RL 0, SRL 0; any 0no Public Assistance recorded0 total; no approved plan
Clinton villageVillagePlan 109006 approved 2023-04-20, pending adoption here; not yet eligibleFMA RL 0, SRL 0; any 0$6,742.4731 total; no approved plan
Edgerton cityCityApproved, expires 2028-04-19FMA RL 0, SRL 0; any 0$18,189.2330 total; 4 since its planAlso approved under plan 108424 (Dane County, expires 2027-12-06). FEMA's plan status map shows one plan per jurisdiction and may show one of these; this packet uses the approved plan that expires last.
Evansville cityCityApproved, expires 2028-04-19FMA RL 0, SRL 0; any 0$76,213.3659 total; 10 since its plan
Footville villageVillageApproved, expires 2028-04-19FMA RL 0, SRL 0; any 0$64,215.408 total; 0 since its plan
Janesville cityCityPlan 109006 approved 2023-04-20, pending adoption here; not yet eligibleFMA RL 0, SRL 1; any 3$842,346.3064 total; no approved plan
Milton cityCityApproved, expires 2028-04-19FMA RL 0, SRL 0; any 0$42,065.8659 total; 7 since its plan
Orfordville villageVillageApproved, expires 2028-04-19FMA RL 0, SRL 0; any 0$5,455.3542 total; 2 since its plan
Harmony townTownApproved, expires 2028-04-19$3,155.690 total; 0 since its planNo NFIP community ID on this jurisdiction's plan row.
La Prairie townTownApproved, expires 2028-04-19no Public Assistance recorded0 total; 0 since its planNo NFIP community ID on this jurisdiction's plan row.
Milton townTownApproved, expires 2028-04-19$32,844.1759 total; 7 since its planNo NFIP community ID on this jurisdiction's plan row.
Plymouth townTownApproved, expires 2028-04-19$4,557.500 total; 0 since its planNo NFIP community ID on this jurisdiction's plan row.
Spring Valley townTownApproved, expires 2028-04-19no Public Assistance recorded0 total; 0 since its planNo NFIP community ID on this jurisdiction's plan row.

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

HazardBuilding exposuremodeled dollarsAgriculture exposuremodeled dollarsPopulation exposedpeopleEAL buildingsmodeled dollars per yearEAL agriculturemodeled dollars per yearCost of expected deaths and injuriesFEMA's dollar value per year, not property damageEAL as % of exposurebuildings; agriculture where notedStorm Events damage since 2023-04-20county-coded records, property plus crops, nominal dollarsZone-level damage since planproperty plus crops, reported for the zonePublic Assistance since plannominal dollars; see noteNote
Cold Wave$41,011,528,586$379,132,800163,608$176$2,375$12,581,070under 0.0001%$0
Droughtn/a$158,803,049n/an/a$151,897n/a0.0957% (agriculture)NRI has no building exposure for this hazard; agriculture shown
Earthquake$69,552,960,032n/a163,687$429,541n/a$99,0020.000618%
Hail$41,011,528,586$379,132,800163,608$3,578,000$156,891$196,1060.00872%$0
Heat Wave$41,011,528,586$379,132,800163,608$518$4$1,910,181under 0.0001%$0
Hurricane$40,661,698,721$369,472,622162,691$2,736$1,745under $1under 0.0001%
Ice Storm$41,005,449,122n/a163,541$24,305n/a$122,694under 0.0001%
Inland Flooding$40,985,921,051$18,026,2562,395$37,556,698$323,975$23,602n/a (see note)$30,102,000$238,030.72NRI 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$289,889,586n/a1,105$606n/a$2,6730.000209%
Lightning$41,011,528,586n/a163,608$317,335n/a$782,8570.000774%
Strong Wind$41,011,528,586$379,132,800163,608$843,988$123,134$1,046,0000.00206%$110,250$17,000Storm Events damage since the plan includes 1 zone-level High Wind record ($15,000) and 1 zone-level Strong Wind record ($2,000): NOAA non-thunderstorm wind types, outside NRI's Strong Wind definition.
Tornado$41,011,528,586$379,132,800163,608$6,220,713$1,431$6,716,0210.0152%$32,520,000$238,030.72
Wildfire$3,098,089,875$37,539,78314,763$12,686$34$1,6690.000409%
Winter Weather$41,011,528,586$379,132,800163,608$2,057$1,755$110,501under 0.0001%$25,000

Totals since 2023-04-20 (Storm Events through 2026-06-30): 99 county-coded records, 95 with a damage value recorded (including $0), $62,732,250; 36 zone-level records, 36 with a damage value recorded (including $0), $42,000 reported for the zone; Public Assistance: $238,030.72 on 1 counted declaration.

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

MeasureValue
Population163,608
Building value (total, not at risk)$41,011,528,586
Agriculture value (total, not at risk)$379,132,800
NRI risk rating (all hazards)Relatively Moderate
Expected annual loss, buildings and agriculture, all hazards$49,752,600
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)$23,592,374
Social vulnerability ratingVery Low
Community resilience ratingVery High
NRI versionDecember 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

DefinitionPropertiesSevere repetitive lossProperties
Repetitive loss, FMA definition (44 CFR 77.2)1Severe repetitive loss, FMA definition (44 CFR 77.2)1
Repetitive loss, NFIP insurance definition14Severe repetitive loss, NFIP insurance definition1

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

ScopeRL, FMApropertiesSRL, FMApropertiesRL, NFIPpropertiesSRL, NFIPpropertiesAny categorypropertiesMitigatedpropertiesCurrently insuredproperties
County total111411403
of which: Rock County (unincorporated area)1090902
of which: Beloit city0020201
of which: Janesville city0131300
Statewide, no county in FEMA's file0020200

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

JurisdictionNFIP community IDRL, FMApropertiesSRL, FMApropertiesRL, NFIPpropertiesSRL, NFIPpropertiesAny categorypropertiesMitigatedpropertiesCurrently insuredproperties
Rock County5503631090902
Beloit city5555440020201
Brodhead city5501600000000
Clinton village5500670000000
Edgerton city5503650000000
Evansville city5503660000000
Footville village5505750000000
Janesville city5555600131300
Milton city5500260000000
Orfordville village5503690000000

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 groupRL, FMApropertiesSRL, FMApropertiesRL, NFIPpropertiesSRL, NFIPpropertiesAny categorypropertiesMitigatedpropertiesCurrently insuredproperties
single-family residential101001003
2 to 4 unit residential0000000
other residential0000000
non-residential0141400
not reported0000000

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 0 properties are FMA repetitive loss but not NFIP repetitive loss, and 13 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):

  1. FEMA, OpenFEMA HazardMitigationPlanStatuses v1, version 2026-09-29T134039Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/HazardMitigationPlanStatuses (API)
  2. FEMA, OpenFEMA DisasterDeclarationsSummaries v2, version 2026-09-29T162832Z, pulled 2026-09-30, https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries (API)
  3. FEMA, OpenFEMA PublicAssistanceFundedProjectsSummaries v1, version 2026-09-29T150754Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/PublicAssistanceFundedProjectsSummaries (API)
  4. FEMA, OpenFEMA NfipMultipleLossProperties v1, version 2026-08-04T164045Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/NfipMultipleLossProperties (API)
  5. 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)
  6. 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/
  7. 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
  8. 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). Rock County, WI: risk-assessment baseline packet, release 2026-10 (data as of 2026-09-30; County FIPS 55105). Automated baseline. https://hazardplain.org/wi/55105/ 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]