Hazard Plain Automated baseline

St. John Island, VI

Risk-assessment baseline packet

County FIPS:
78020
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 2029-06-30. Plan: U.S. Virgin Islands state-level plan (plan 109955), approved 2024-07-01.

Since the plan was approved on 2024-07-01: 2 new hazard declarations (1 incident): EM-3611-VI (Tropical Storm Ernesto), DR-4841-VI (Tropical Storm Ernesto).

NOAA Storm Events records since that date: 1 record (data through 2026-06-30).

Highest expected annual loss (FEMA National Risk Index, modeled total; see B1-a): Hurricane ($5,423,596 a year), Earthquake ($825,116) and Inland Flooding ($385,830).

Repetitive-loss flood properties now: FMA RL 0, SRL 0 (44 CFR 77.2); any definition: 2.

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 2029-06-30
Plan:
U.S. Virgin Islands state-level plan (plan 109955)
Approved:
2024-07-01
Days to expiry:
1,004

Plan clock from the U.S. Virgin Islands state-level plan; FEMA plan data has no county-level or local plan row for this area.

What changed since your last plan (approved 2024-07-01)

New federal declarations:
2 new hazard declarations (1 incident): EM-3611-VI (Tropical Storm Ernesto), DR-4841-VI (Tropical Storm Ernesto)
Storm Events records since approval:
1 record (data through 2026-06-30)
Repetitive loss now:
FMA RL 0, SRL 0 (44 CFR 77.2); any definition: 2
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

Source: 1

JurisdictionTypeStatusPlanApprovedExpiresDays to expirynegative = days since expiryUpdate underwayNotes
No rows for this unit.

No jurisdictions listed in FEMA plan data for this unit.

Plan 109955 covers 1 other participant: Virgin Islands.

State plan status and tribal plans in this state: see the state page.

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
1HurricaneInsufficient DataRelatively Moderate$5,270,219$0$153,377$5,423,59615Includes 1 Tropical Depression record (outside NRI's Hurricane definition).
2EarthquakeInsufficient DataRelatively Low$703,745n/a$121,371$825,116Storm Events does not record earthquakes.
3Inland FloodingInsufficient DataVery Low$384,438$0$1,392$385,83011
4TsunamiInsufficient DataVery Low$70,188n/a$0$70,1880No recorded events in Storm Events since 1996 (data through 2026-06-30).
5Coastal FloodingInsufficient DataVery Low$12,302n/a$204$12,5062
6TornadoInsufficient DataVery Low$359$0$175$5340No recorded events in Storm Events since 1996 (data through 2026-06-30).
7Volcanic ActivityInsufficient DataVery Low$1n/a$93$935
8HailInsufficient DataVery Low$41$0$3$440No recorded events in Storm Events since 1996 (data through 2026-06-30).
9Strong WindInsufficient DataVery Low$10$0$3$135Includes 2 Strong Wind records (a NOAA non-thunderstorm wind type, outside NRI's Strong Wind definition).
10Cold WaveInsufficient DataNo Expected Annual Losses$0$0$0$00No recorded events in Storm Events since 1996 (data through 2026-06-30).
11DroughtInsufficient DataNo Expected Annual Lossesn/a$0n/a$013
12Heat WaveInsufficient DataNo Expected Annual Losses$0$0$0$02
13Winter WeatherInsufficient DataNo Expected Annual Losses$0$0$0$00No recorded events in Storm Events since 1996 (data through 2026-06-30).
LandslideInsufficient DataInsufficient Datan/an/an/an/a0Declared 5 times; no Storm Events record of this type.
LightningInsufficient DataInsufficient Datan/an/an/an/a0No recorded events in Storm Events since 1996 (data through 2026-06-30).
WildfireInsufficient DataInsufficient Datan/an/an/an/a0No 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 tsunami, tornado, hail, cold wave, winter weather, landslide, lightning and wildfire 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 and ice storm. 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, 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

HazardHighest-rated census tractsNRI risk rating, score 0 to 100
Earthquakeno tract has a National Risk Index rating for this hazard
Hurricaneno tract has a National Risk Index rating for this hazard
Landslideno tract has a National Risk Index rating for this hazard
Tornadono tract has a National Risk Index rating for this hazard
Tsunamino tract has a National Risk Index rating for this hazard
Volcanic Activityno tract has a National Risk Index rating for this hazard
Wildfireno tract has a National Risk Index rating for this hazard

Up to 3 census tracts per hazard, highest National Risk Index rating first, then highest score; a tract number is the Census tract number. 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
Coastal Flood, Storm Surge/Tidenone in data (flood depth: FIRM)2 records, 2022 to 2024 (2 zone-level)No damage reported in 2 records.Countywide (zone-level records).Flood depth: see the FEMA Flood Insurance Rate Map.
Cold/Wind Chill, Extreme Cold/Wind Chillwind chill0Wind chill: in event narratives only (local data needed).
Frost/Freeze (outside NRI's Cold Wave definition)crop damage0Temperature: in event narratives only (local data needed).
DroughtU.S. Drought Monitor scale (D0 to D4)13 records, 1997 to 2024 (13 zone-level)31 days to 166 days (median 87 days); 4 with a recorded value166 days (about 5.5 months), 2023-09-01 to 2024-02-13, a run of 6 consecutive Storm Events drought records, zone-levelCountywide (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)0
Excessive Heat, Heatheat index (in event narratives)2 records, 2023 to 2024 (2 zone-level)1 day to 30 days (median 15.5 days); 2 with a recorded valueSeptember 2023 (1 monthly summary record), zone-levelCountywide (zone-level records).Heat index: in event narratives only (local data needed).
Hurricane, Tropical Storm, Tropical DepressionSaffir-Simpson15 records, 1997 to 2021 (15 zone-level)Strongest recorded: Hurricane (Typhoon) record (NOAA's event type name), 2000-08-22, $100,000 property; crops not reported (2000 dollars); NWS zone VIZ001Most damaging recorded: Tropical Storm, 2004-09-14, $2,400,000 property; crops not reported, reported for the zone (2004 dollars)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.
Flash Flood, Flood, Lakeshore Flooddamage and flood days (flood depth: FIRM)11 records, 1999 to 2018 (2 zone-level)Flood, 2003-11-11, $500,000 property; crops not reported (2003 dollars); NWS zone VIZ001No event record names a jurisdiction in the plan. Zone-level records (2) 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)0Physical measure: in event narratives only (local data needed).
Lightningannualized frequency (the measure FEMA's Local Mitigation Planning Handbook names)0Storm Events lists lightning with damage or casualties; physical measure in event narratives only (local data needed).
High Wind and Strong Wind (outside NRI's Strong Wind definition)wind speed (kt and mph)2 records, 2007 to 2010 (2 zone-level)42 kt (48 mph) to 46 kt (53 mph) (median 44 kt (51 mph)); 2 with a recorded value46 kt (53 mph) measured gust, Strong Wind, 2010-08-30; NWS zone VIZ001Countywide (zone-level records).
Thunderstorm Windwind speed (kt and mph)3 records, 1998 to 2011 (1 zone-level)41 kt (47 mph); 1 with a recorded value41 kt (47 mph) measured gust, Thunderstorm Wind, 2011-07-01Thunderstorm Wind, 2002-09-16, $10,000 property; crops not reported, reported for the zone (2002 dollars)No event record names a jurisdiction in the plan. Zone-level records (1) apply countywide.
TornadoEnhanced Fujita (Fujita before Feb 2007)0Before 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).
Tsunaminone (count and damage only)0Physical measure: in event narratives only (local data needed).
Volcanic Ash, Volcanic AshfallVolcanic Explosivity Index (local data)5 records, 2001 to 2008 (5 zone-level)Volcanic Ash, 2001-07-29, $100,000 property; crops not reported (2001 dollars); NWS zone VIZ001Countywide (zone-level records).Physical measure: in event narratives only (local data needed).
Wildfireacres burned (local data)0Acres burned: in event narratives only (local data needed).
Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleetnone in data (snowfall: local data)0Snow depth: in event narratives only (local data needed).

Storm Events records are more complete after 1996; before 1996 only Tornado (from 1950), Hail and Thunderstorm Wind (from 1955) exist. Zone-level records whose zone 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.

A monthly summary record covers most or all of a month; it does not count days at wave conditions.

Supports FEMA checklist item B1-d: previous occurrences

Federal declarations for this county: 27 declarations covering 21 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
2024-10-252024-08-13DR-4841-VIMajor disasterTropical Storm ErnestoHurricaneno Public Assistance recordednew since last plan; within last 5 years
2024-08-182024-08-13EM-3611-VIEmergencyTropical Storm ErnestoHurricane (primary); also designated: Landslideno Public Assistance recordednew since last plan; within last 5 yearssame incident as DR-4841
2020-07-292020-07-27EM-3531-VIEmergencyPotential Tropical Cyclone NineHurricaneno Public Assistance recorded
2020-04-022020-01-20DR-4513-VIMajor disasterCOVID-19 PandemicNon-natural, not countedno Public Assistance recorded
2020-03-132020-01-20EM-3433-VIEmergencyCOVID-19Non-natural, not countedno Public Assistance recordedsame incident as DR-4513
2019-08-282019-08-26EM-3418-VIEmergencyHurricane DorianHurricaneno Public Assistance recorded
2017-09-202017-09-16DR-4340-VIMajor disasterHurricane MariaHurricane$21,726.87
2017-09-182017-09-16EM-3390-VIEmergencyHurricane MariaHurricaneno Public Assistance recordedsame incident as DR-4340
2017-09-072017-09-05DR-4335-VIMajor disasterHurricane IrmaHurricane$8,885.08
2017-09-052017-09-05EM-3383-VIEmergencyHurricane IrmaHurricaneno Public Assistance recordedsame incident as DR-4335
2010-11-052010-10-01DR-1948-VIMajor disasterSevere Storms, Flooding, Mudslides, and LandslidesInland Flooding; Landslideno Public Assistance recorded
2010-09-282010-08-29DR-1939-VIMajor disasterHurricane EarlHurricaneno Public Assistance recorded
2008-10-292008-10-14DR-1807-VIMajor disasterHurricane OmarHurricaneno Public Assistance recorded
2004-10-072004-09-14DR-1567-VIMajor disasterTropical Storm JeanneHurricaneno Public Assistance recorded
2003-12-092003-11-10DR-1503-VIMajor disasterSevere Storms, Flooding, Landslides, and MudslidesInland Flooding; Landslideno Public Assistance recorded
1999-11-231999-11-17DR-1309-VIMajor disasterHurricane Lenny Major DeclarationHurricaneno Public Assistance recorded
1999-11-171999-11-17EM-3152-VIEmergencyHurricane LennyHurricaneno Public Assistance recordedsame incident as DR-1309
1998-09-241998-09-19DR-1248-VIMajor disasterHurricane Georges - 18 Sep 98Hurricaneno Public Assistance recorded
1996-07-111996-07-08DR-1126-VIMajor disasterHurricane BerthaHurricaneno Public Assistance recorded
1995-09-161995-09-15DR-1067-VIMajor disasterHurricane MarilynHurricaneno Public Assistance recorded
1989-09-201989-09-17DR-841-VIMajor disasterHurricane HugoHurricaneno Public Assistance recorded
1984-12-101984-11-05DR-729-VIMajor disasterTropical Storm KlausHurricaneno Public Assistance recorded
1983-04-301983-04-30DR-681-VIMajor disasterSevere Storms, Flooding & MudslidesInland Flooding (primary); also designated: Landslideno Public Assistance recorded
1979-09-161979-09-16DR-602-VIMajor disasterHurricane David, Tropical Storm FredericHurricaneno Public Assistance recorded
1977-06-141977-06-14EM-3042-VIEmergencyDroughtDroughtno Public Assistance recorded
1974-11-141974-11-14DR-451-VIMajor disasterSevere Storms, Landslides & FloodingInland Flooding (primary); also designated: Landslideno Public Assistance recorded
1970-10-171970-10-17DR-298-VIMajor disasterHeavy Rains & 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.

Statewide declarations

Source: 2

DeclaredIncident beganFEMA numberTypeTitleMapped hazard
1998-09-211998-09-21EM-3129-VIEmergencyHurricane Georges (Direct Federal Assist First 72 Hrs)Hurricane
1964-06-081964-06-08DR-171-VIMajor disasterExtreme Drought ConditionsDrought

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.

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
Coastal Flooding2012001996 to 2026-06-30
Cold Wave0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Drought130712101996 to 2026-06-30
Earthquake000000Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hail0000001955 to 2026-06-30No recorded events, 1955 to 2026-06-30, NOAA NCEI Storm Events
Heat Wave2112001996 to 2026-06-30
Hurricane150001511996 to 2026-06-30Includes 1 Tropical Depression record.
Inland Flooding11000501996 to 2026-06-30
Landslide0000511996 to 2026-06-30No Storm Events records of this type; 5 federal declared incidents (see declarations table)
Lightning0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Strong Wind5000001955 to 2026-06-30Includes 2 Strong Wind records.
Tornado0000001950 to 2026-06-30No recorded events, 1950 to 2026-06-30, NOAA NCEI Storm Events
Tsunami0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Volcanic Activity5000001996 to 2026-06-30
Wildfire0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Winter Weather0000001996 to 2026-06-30No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events

Notable Storm Events records

Sources: 1, 6, 7

DateEvent typeMagnitude or extentDamagenominal dollarsDeaths, injuriesdirect onlyLocationFlagsWhy listed
2023-09-01Drought$0 property; $0 crops, reported for the zone (2023 dollars)0, 0NWS zone VIZ001 (ST. THOMAS / ST. JOHN AND ADJACENT ISLANDS), zone-levelin the 12 months before plan approval; within last 5 yearsB1-c worst recorded: Drought
2023-09-01Excessive Heat$0 property; $0 crops, reported for the zone (2023 dollars)0, 0NWS zone VIZ001 (ST. THOMAS / ST. JOHN AND ADJACENT ISLANDS), zone-levelin the 12 months before plan approval; within last 5 yearsB1-c worst recorded: Excessive Heat, Heat
2011-07-01Thunderstorm Wind41 kt (47 mph) measured gust$100 property; $0 crops (2011 dollars)0, 0ST JOHNB1-c worst recorded: Thunderstorm Wind
2010-08-30Strong Wind46 kt (53 mph) measured gust$30,000 property; $0 crops, reported for the zone (2010 dollars)0, 0NWS zone VIZ001 (ST. THOMAS / ST. JOHN AND ADJACENT ISLANDS), zone-levelB1-c worst recorded: High Wind and Strong Wind
2004-09-14Tropical Storm$2,400,000 property; crops not reported, reported for the zone (2004 dollars)0, 0NWS zone VIZ001 (ST. THOMAS / ST. JOHN AND ADJACENT ISLANDS), zone-levelB1-c most damaging: Hurricane, Tropical Storm, Tropical Depression
2003-11-11Flood$500,000 property; crops not reported, reported for the zone (2003 dollars)0, 0NWS zone VIZ001 (ST. THOMAS / ST. JOHN AND ADJACENT ISLANDS), zone-levelB1-c worst recorded: Flash Flood, Flood, Lakeshore Flood
2002-09-16Thunderstorm Windspeed not recorded$10,000 property; crops not reported, reported for the zone (2002 dollars)0, 0Storm Events area ST. THOMAS/ST. JOHN & ISLANDS (legacy zone code VIZ001), zone-levelB1-c most damaging: Thunderstorm Wind
2001-07-29Volcanic Ash$100,000 property; crops not reported, reported for the zone (2001 dollars)0, 0NWS zone VIZ001 (ST. THOMAS / ST. JOHN AND ADJACENT ISLANDS), zone-levelB1-c worst recorded: Volcanic Ash, Volcanic Ashfall
2000-08-22Hurricane (Typhoon), NOAA's event type name$100,000 property; crops not reported, reported for the zone (2000 dollars)0, 0NWS zone VIZ001 (ST. THOMAS / ST. JOHN AND ADJACENT ISLANDS), zone-levelB1-c worst recorded: Hurricane, Tropical Storm, Tropical Depression
1998-06-21Thunderstorm Windspeed not recorded$5,000 property; crops not reported (1998 dollars)0, 0COUNTYWIDElarge reported damage

The full list is in the Excel file, sheet "B1-d Storm Events history" (53 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).

FEMA's declaration data list no tribal or special-area declarations for this state.

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
Coastal Flooding0.21events per year at a location (modeled)about 0.21 per year at a given location in the countyPossible (from Storm Events: 2 of 30 years)Storm Events records in 2 of 30 years, 1996 to 2025 (6.67%)not shownmodeledsee B1-fDescriptor from Storm Events, not NRI.
Cold Wave0event-days per yearnone modeledevent-days in 0 of 30 years, 1996 to 2025 (0%)02005-11-12 to 2024-11-12 (19 years)countywideNo Storm Events cold wave record, 1996 to 2025.
Drought0event-days per yearnone modeledLikely (from Storm Events: 4 of 30 years)event-days in 4 of 30 years, 1996 to 2025 (13.3%)02000 to 2025 (25.25 years; D3 and D4 only)countywideNRI models no drought event-days here (2000 to 2025, 25.25 years; D3 and D4 only); Storm Events has a record in 4 of 30 years. The descriptor comes from Storm Events, which counts D2 drought that NRI leaves out.
Earthquake0.127annual probability at a locationchance a given location in the county has at least minor-damage shaking in a year: 12.7%not shownmodeledsee B1-fNo descriptor (Storm Events does not record earthquakes).
Hail0.00166events per yearabout 1 in 602 yearsUnlikelyFEMA annualized frequency (modeled)0.1 (modeled)1986 to 2023 (38 years)countywide
Heat Wave0event-days per yearnone modeledPossible (from Storm Events: 2 of 30 years)event-days in 2 of 30 years, 1996 to 2025 (6.67%)02005-11-12 to 2024-11-12 (19 years)countywideNRI models no heat wave event-days here (2005-11-12 to 2024-11-12, 19 years); Storm Events has a record in 2 of 30 years. The descriptor comes from Storm Events, which records events NRI's definition leaves out.
Hurricane0.265events per yearabout 1 in 4 yearsLikelyFEMA annualized frequency (modeled)611851 to 2024 (Atlantic)see B1-fNRI counts hurricane and tropical storm tracks passing within storm-force wind range; federal declarations are in B1-d.
Inland Flooding0.321event-days per yearabout 0.321 days per yearLikely (from Storm Events: 8 of 30 years)event-days in 8 of 30 years, 1996 to 2025 (26.7%)91996 to 2023 (28 years)see B1-f
Landslideevents per year (modeled)not shownmodeledsee B1-fNRI publishes no annualized frequency for this hazard in this county.
Lightningdays per year with a strikenot shown1995 to 2023 (29 years; CONUS)countywideDescriptor not assigned: NRI publishes no lightning frequency for this county.
Strong Wind0.00166events per yearabout 1 in 602 yearsUnlikelyFEMA annualized frequency (modeled)11986 to 2023 (38 years)countywide
Tornado0.000484events per yearabout 1 in 2,067 yearsUnlikelyFEMA annualized frequency (modeled)not shown1950 to 2023 (EF2+); 1986 to 2023 (EF0-1)see B1-f
Tsunami0.0419annual probability at the most exposed location (used in place of a county value)chance at the county's most exposed location in a year: 4.19%Storm Events records in 0 of 30 years, 1996 to 2025 (0%)not shownmodeledsee B1-fNo descriptor: no Storm Events record 1996 to 2025
Volcanic Activity0.0101annual probabilityabout 1 in 99 yearsPossibleFEMA annualized frequency (modeled)not shownmodeledsee B1-f
Wildfireannual probability at a locationStorm Events records in 0 of 30 years, 1996 to 2025 (0%)not shownmodeledsee B1-fNo descriptor: no Storm Events record 1996 to 2025
Winter Weather0event-days per yearnone modeledevent-days in 0 of 30 years, 1996 to 2025 (0%)02005-11-12 to 2024-11-12 (19 years)countywideNo Storm Events winter weather record, 1996 to 2025

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.

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 20250300
Hail2.00 in+1996 to 20250300
Thunderstorm Wind (counted as NRI Strong Wind)50-64 kt1996 to 20250300
Thunderstorm Wind (counted as NRI Strong Wind)65 kt+1996 to 20250300
Thunderstorm Wind (counted as NRI Strong Wind)unmeasured or below 50 kt1996 to 20252300.0667
TornadoEF0-11996 to 20250300
TornadoEF2-31996 to 20250300
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
Coastal Flooding0 of 2Insufficient Data 2
Cold Wave0 of 2Insufficient Data 2
Drought0 of 2Insufficient Data 2
Earthquake0 of 2Insufficient Data 2
Hail0 of 2Insufficient Data 2
Heat Wave0 of 2Insufficient Data 2
Hurricane0 of 2Insufficient Data 2
Inland Flooding0 of 2Insufficient Data 2
Landslide0 of 2Insufficient Data 2
Lightning0 of 2Insufficient Data 2
Strong Wind0 of 2Insufficient Data 2
Tornado0 of 2Insufficient Data 2
Tsunami0 of 2Insufficient Data 2
Volcanic Activity0 of 2Insufficient Data 2
Wildfire0 of 2Insufficient Data 2
Winter Weather0 of 2Insufficient Data 2

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.

This county has 2 census tracts; the minimum, median and maximum come from those 2.

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
No rows for this unit.

No city, town, township or county rows in FEMA plan data for this unit; same as county.

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 2024-07-01county-coded records, property plus crops, nominal dollarsZone-level damage since planproperty plus crops, reported for the zonePublic Assistance since plannominal dollars; see noteNote
Coastal Flooding$144,990,986n/a202$12,302n/a$2040.00848%
Cold Wave$0$00$0$0$0building exposure is 0 in NRI
Droughtn/a$0n/an/a$0n/aagriculture exposure is 0 in NRI
Earthquake$2,218,408,546n/a3,882$703,745n/a$121,3710.0317%
Hail$1,386,875,198$03,882$41$0$3under 0.0001%
Heat Wave$0$00$0$0$0$0building exposure is 0 in NRI
Hurricane$1,386,875,198$03,882$5,270,219$0$153,3770.38%no Public Assistance recorded (2 declarations)
Inland Flooding$1,375,018,640$0199$384,438$0$1,392n/a (see note)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.
Landsliden/an/an/an/an/an/ano Public Assistance recorded (1 declaration)NRI publishes no building exposure for this county
Lightningn/an/an/an/an/an/aNRI publishes no building exposure for this county
Strong Wind$1,386,875,198$03,882$10$0$3under 0.0001%
Tornado$1,386,875,198$03,882$359$0$175under 0.0001%
Tsunami$1,179,399,465n/a342$70,188n/a$00.00595%
Volcanic Activity$1,386,875,198n/a3,882$1n/a$93under 0.0001%
Wildfiren/an/an/an/an/an/aNRI publishes no building exposure for this county
Winter Weather$0$00$0$0$0building exposure is 0 in NRI

Totals since 2024-07-01 (Storm Events through 2026-06-30): 0 county-coded records, 0 with a damage value recorded (including $0), $0; 1 zone-level records, 1 with a damage value recorded (including $0), $0 reported for the zone; Public Assistance: none recorded on the 2 counted declarations.

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
Population3,882
Building value (total, not at risk)$1,386,875,198
Agriculture value (total, not at risk)$0
NRI risk rating (all hazards)Insufficient Data
Expected annual loss, buildings and agriculture, all hazards$6,441,301
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)$276,619
Social vulnerability ratingData Unavailable
Community resilience ratingData Unavailable
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)0Severe repetitive loss, FMA definition (44 CFR 77.2)0
Repetitive loss, NFIP insurance definition2Severe repetitive loss, NFIP insurance definition0

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 total0020200
of which: Territory of Virgin Islands (community ID not in plan data)0020200
Statewide, no county in FEMA's file011011000

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.

County repeat-flood properties by occupancy group

Sources: 1, 4

Occupancy groupRL, FMApropertiesSRL, FMApropertiesRL, NFIPpropertiesSRL, NFIPpropertiesAny categorypropertiesMitigatedpropertiesCurrently insuredproperties
single-family residential0020200
2 to 4 unit residential0000000
other residential0000000
non-residential0000000
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 2 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, organized by the items of FEMA's Local Mitigation Plan Review Tool, Element B. Each section heading names the item its tables support; the plan and FEMA's review decide whether the 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). St. John Island, VI: risk-assessment baseline packet, release 2026-10 (data as of 2026-09-30; County FIPS 78020). Automated baseline. https://hazardplain.org/vi/78020/ 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: contact@hazardplain.org

Hazard Plain release 2026-10. As of 2026-09-30; Storm Events data through 2026-06-30. Automated baseline.