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Natural hazard risk in Nassau County, New York

Updated October 30, 2026. Based on FEMA, NOAA and OpenFEMA data. Published by Humblebee.

FEMA overall Risk Index rating: Relatively High (score 97.1 of 100)[5]

Expected annual loss (FEMA)
$298.6 million[1]
Federal disaster declarations since 1965
27[2]
NFIP flood claims paid, 1978 to 2026
$2.28 billion[3]
Tornadoes recorded, 1950 to 2024
9[4]

FEMA's National Risk Index rates the overall natural hazard risk for Nassau County Relatively High compared with other US counties, with a Risk Index score of 97.1 out of 100[5]. Within the county, the hazards with the highest FEMA scores are winter weather, ice storm and coastal flooding, all rated Very High[6].

FEMA risk ratings for each hazard

Ratings and expected losses from the FEMA National Risk Index. Each rating compares this county with all US counties for that hazard, from Very Low to Very High. They are planning estimates, not predictions, and they do not describe any single property.

FEMA's National Risk Index estimates Expected Annual Loss from all 18 natural hazards in Nassau County at $298.6 million a year, rated Relatively High[1]. This is FEMA's estimate of average yearly economic loss, not money anyone paid, and it does not predict next year's losses[7]. Inland flooding accounts for the largest share, at $183.9 million a year[8], followed by earthquake at $28.0 million[9], hurricane at $27.1 million[10] and coastal flooding at $24.3 million[11]. FEMA rates Social Vulnerability in the county Relatively Low (score 25.8), which describes how susceptible social groups are to the harm hazards cause[12]. FEMA rates Community Resilience Very High (score 97.0), which describes the ability to prepare for, withstand and recover from hazards[13].

Hazards sorted by FEMA hazard-type Risk Index score, highest first
HazardFEMA risk ratingExpected annual loss
Winter WeatherVery High$2.0 million[14]
Ice StormVery High$3.9 million[15]
Coastal FloodingVery High$24.3 million[11]
Inland FloodingRelatively High$183.9 million[8]
LightningVery High$3.0 million[16]
Strong WindRelatively High$4.5 million[17]
EarthquakeRelatively Moderate$28.0 million[9]
Heat WaveRelatively Moderate$8.3 million[18]
HurricaneRelatively High$27.1 million[10]
Cold WaveRelatively High$9.9 million[19]
TornadoRelatively Moderate$3.7 million[20]
LandslideRelatively Low$11,000[21]
WildfireVery Low$36,000[22]
HailVery Low$96,000[23]
DroughtVery Low$2,412[24]

Rated Not Applicable by FEMA for this county: avalanche, volcanic activity[25].

Social vulnerability and community resilience

FEMA uses these two ratings to scale expected losses into the Risk Index.

FEMA measureRatingScore
Social vulnerabilityRelatively Low25.8[12]
Community resilienceVery High97.0[13]

Flooding and flood insurance

FEMA rates coastal flooding risk in Nassau County Very High (score 98.4)[11] and inland flooding risk Relatively High (score 98.2)[8] compared with other US counties. OpenFEMA data show 35,824 residential flood insurance contracts in force out of 371,341 residential structures, a penetration rate of 9.7%, and 76.2% inside FEMA's mapped Special Flood Hazard Area (as of 2026-08-03)[26]. From 1978 to 2026, 51,523 National Flood Insurance Program claims were filed for losses in the county, and NFIP paid $2.28 billion in total[3]. The year with the most paid claims was 2012, with 25,951[3].

Measure Value
Coastal Flooding, FEMA risk rating[11] Very High, $24.3 million expected loss a year
Inland Flooding, FEMA risk rating[8] Relatively High, $183.9 million expected loss a year
NFIP residential flood policies in force (2026)[26] 35,824 of 371,341 homes
Homes in FEMA's mapped high-risk flood area (SFHA)[26] 35,643, of which 27,164 insured
NFIP flood claims, 1978 to 2026[3] 51,523 filed, $2.28 billion paid

Is a specific address in a flood zone? Only FEMA's flood maps answer that, property by property[27]. This page describes the whole county.

Search an address on the FEMA Flood Map Service Center

Disaster declarations and tornado records

OpenFEMA lists 27 federal disaster declarations for natural hazards that include Nassau County since 1965, of which 12 were for hurricanes, 6 for severe storms and 4 for floods[2]. The most recent was DR-4755-NY, Severe Storm And Flooding, declared 2024-01-30[28]. NOAA's Storm Prediction Center tornado database records 9 tornadoes in the county from 1950 to 2024, with the strongest rated F2 and none rated F3/EF3 or stronger[4]. The most recent recorded tornado was on 2021-11-13[4].

Federal disaster declarations for natural hazards that include Nassau County, since 1965
Incident type Declarations
Hurricane[2] 12
Severe Storm[2] 6
Flood[2] 4
Snowstorm[2] 3
Drought[2] 1
Fire[2] 1
Most recent declarations
Declaration Incident Declared
DR-4755-NY[28] Severe Storm And Flooding 2024-01-30
DR-4615-NY[28] Remnants Of Hurricane Ida 2021-09-05
EM-3572-NY[28] Remnants Of Hurricane Ida 2021-09-02
EM-3565-NY[28] Hurricane Henri 2021-08-22
DR-4567-NY[28] Tropical Storm Isaias 2020-10-02

How to prepare

Steps from Ready.gov, FEMA's preparedness site, for the hazards with the highest FEMA ratings here. Follow instructions from local officials and the National Weather Service when a warning is issued.

Winter storms and cold

Before

  • Insulate your home and learn how to keep pipes from freezing.
  • Install and test smoke and carbon monoxide detectors with battery backup.
  • Keep several days of supplies in case the power goes out, including medication and pet needs.
  • Put an emergency kit in your car with jumper cables, sand, blankets, water and snacks, and keep the tank full.

During

  • Under a winter storm warning, find shelter right away.
  • Stay off the roads if you can. If you are stuck in your car, stay inside it.
  • Run generators and grills only outdoors, away from windows, and never heat your home with an oven or stove.

Source: Ready.gov, winter storms and cold

Floods

Before

  • Check your flood risk with FEMA's Flood Map Service Center, and remember that floods do not follow map lines.
  • Sign up for your community's warning system. NOAA Weather Radio also broadcasts alerts.
  • Buy flood insurance through the NFIP well before a disaster. Homeowners policies do not cover flooding, and a new policy typically takes up to 30 days to go into effect.
  • Make a household plan with evacuation routes, shelter locations and what to do in a flash flood.
  • Keep important documents in a waterproof container and make password-protected digital copies.

During

  • If you are told to evacuate, leave right away and never drive around barricades.
  • Do not walk, swim or drive through floodwater. Six inches of moving water can knock you down.
  • If you are trapped in a building, go to the highest level, but do not climb into a closed attic.

Source: Ready.gov, floods

Earthquakes

Before

  • Practice Drop, Cover, and Hold On with your family and coworkers.
  • Sign up for earthquake alerts that can warn you before shaking starts.
  • Make a plan with an out-of-state contact and a place to meet if you get separated.
  • Anchor heavy items such as bookcases, refrigerators and water heaters, and keep heavy things on low shelves.
  • Consider earthquake insurance. Standard homeowners policies do not cover earthquake damage.

During

  • Drop to your hands and knees, cover your head and neck, and hold on until the shaking stops.
  • Indoors, stay where you are and avoid doorways. Outdoors, move to an open area away from buildings and power lines.
  • If you are driving, pull over, stop and set the parking brake.

Source: Ready.gov, earthquakes

Questions people ask

Is Nassau County at risk of flooding?
FEMA rates coastal flooding risk Very High[11] and inland flooding risk Relatively High[8] compared with other US counties. NFIP paid $2.28 billion on flood claims in the county for losses from 1978 to 2026[3].
How do I check if a Nassau County address is in a flood zone?
Look up the address on FEMA's Flood Map Service Center or ask the local floodplain manager[27]. County-level ratings do not tell you the flood zone of a single address[27].
Does Nassau County get hurricanes?
FEMA rates hurricane risk in Nassau County Relatively High, with Expected Annual Loss of $27.1 million a year[10]. OpenFEMA lists 12 hurricane disaster declarations that include the county since 1965[2].
Does Nassau County get tornadoes?
NOAA's tornado database records 9 tornadoes in Nassau County from 1950 to 2024, the strongest rated F2[4]. FEMA rates tornado risk Relatively Moderate compared with other US counties[20].
How many federal disasters have been declared in Nassau County?
OpenFEMA lists 27 federal disaster declarations for natural hazards that include Nassau County since 1965, 20 of them major disasters[2].

Facts and sources

  1. FEMA National Risk Index (version 1.20, December 2025): Expected Annual Loss from all 18 natural hazards in Nassau County is $298.6 million a year (Expected Annual Loss rating Relatively High, score 97.6). Of this, buildings account for $253.7 million, injuries and deaths (converted to dollars by FEMA) for $44.9... FEMA National Risk Index
  2. OpenFEMA Disaster Declarations Summaries list 27 federal disaster declarations for natural hazards that include Nassau County since 1965 (20 major disaster, 7 emergency or fire management). By incident type: hurricane 12, severe storm 6, flood 4, snowstorm 3, drought 1, fire 1. Biological (such as COVID-19) and... OpenFEMA Disaster Declarations
  3. HazardFacts tally of OpenFEMA NFIP Redacted Claims (losses from 1978 to 2026): 51,523 National Flood Insurance Program claims were filed for losses in Nassau County, 44,579 of them with a payment, and NFIP paid $2.28 billion in total (building, contents and increased cost of compliance, in dollars of the year... OpenFEMA NFIP claims
  4. NOAA Storm Prediction Center tornado database (1950 to 2024): 9 recorded tornadoes touched Nassau County. The strongest were rated F2 (most recent of them on 1998-09-07). 0 were rated F3/EF3 or stronger. The most recent recorded tornado was on 2021-11-13. Ratings used the Fujita scale until early 2007 and the... NOAA Storm Prediction Center
  5. FEMA National Risk Index (version 1.20, December 2025): the overall natural hazard Risk Index rating for Nassau County is Relatively High, with a Risk Index score of 97.1 out of 100. The score is the county's percentile rank among all US counties. FEMA National Risk Index
  6. Among the 18 hazards in the FEMA National Risk Index (version 1.20, December 2025), the hazards with the highest hazard-type Risk Index scores for Nassau County are winter weather (98.9, Very High), ice storm (98.7, Very High), coastal flooding (98.4, Very High). HazardFacts sorted FEMA's published scores; FEMA's... FEMA National Risk Index
  7. FEMA's National Risk Index FAQ (December 2025): Expected Annual Loss is FEMA's estimate of the average economic loss in dollars from natural hazards each year. The index is not meant to predict how much damage a community will have in the next year, and a hazard can still cause damage where a rating is low. Scores... FEMA National Risk Index documentation
  8. FEMA National Risk Index (version 1.20, December 2025), inland flooding in Nassau County: Risk Index rating Relatively High (score 98.2 of 100). Expected Annual Loss $183.9 million a year (rating Relatively High). Annualized frequency 3.29 event-days per year, from recorded occurrences over a period of record of 26... FEMA National Risk Index
  9. FEMA National Risk Index (version 1.20, December 2025), earthquake in Nassau County: Risk Index rating Relatively Moderate (score 96.4 of 100). Expected Annual Loss $28.0 million a year (rating Relatively High). FEMA's modeled annual frequency is 0.0019 events per year. FEMA National Risk Index
  10. FEMA National Risk Index (version 1.20, December 2025), hurricane in Nassau County: Risk Index rating Relatively High (score 95.4 of 100). Expected Annual Loss $27.1 million a year (rating Relatively High). Annualized frequency 0.17 events per year, from recorded occurrences over a period of record of 172 years for... FEMA National Risk Index
  11. FEMA National Risk Index (version 1.20, December 2025), coastal flooding in Nassau County: Risk Index rating Very High (score 98.4 of 100). Expected Annual Loss $24.3 million a year (rating Very High). FEMA's modeled annual frequency is 3.8346 events per year. FEMA National Risk Index
  12. FEMA National Risk Index (version 1.20, December 2025): Social Vulnerability rating for Nassau County is Relatively Low (score 25.8). FEMA describes social vulnerability as how susceptible social groups are to the harm natural hazards cause. FEMA National Risk Index
  13. FEMA National Risk Index (version 1.20, December 2025): Community Resilience rating for Nassau County is Very High (score 97.0). FEMA describes community resilience as a community's ability to prepare for, withstand and recover from hazards. FEMA National Risk Index
  14. FEMA National Risk Index (version 1.20, December 2025), winter weather in Nassau County: Risk Index rating Very High (score 98.9 of 100). Expected Annual Loss $2.0 million a year (rating Very High). Annualized frequency 9.75 events per year, from recorded occurrences over a period of record of 18 years. FEMA National Risk Index
  15. FEMA National Risk Index (version 1.20, December 2025), ice storm in Nassau County: Risk Index rating Very High (score 98.7 of 100). Expected Annual Loss $3.9 million a year (rating Very High). Annualized frequency 0.72 event-days per year, from recorded occurrences over a period of record of 68 years. FEMA National Risk Index
  16. FEMA National Risk Index (version 1.20, December 2025), lightning in Nassau County: Risk Index rating Very High (score 97.3 of 100). Expected Annual Loss $3.0 million a year (rating Very High). Annualized frequency 27.27 events per year, from recorded occurrences over a period of record of 24 years. FEMA National Risk Index
  17. FEMA National Risk Index (version 1.20, December 2025), strong wind in Nassau County: Risk Index rating Relatively High (score 97.1 of 100). Expected Annual Loss $4.5 million a year (rating Relatively High). Annualized frequency 4.87 events per year, from recorded occurrences over a period of record of 38 years. FEMA National Risk Index
  18. FEMA National Risk Index (version 1.20, December 2025), heat wave in Nassau County: Risk Index rating Relatively Moderate (score 95.9 of 100). Expected Annual Loss $8.3 million a year (rating Relatively Moderate). Annualized frequency 5.82 event-days per year, from recorded occurrences over a period of record of 18... FEMA National Risk Index
  19. FEMA National Risk Index (version 1.20, December 2025), cold wave in Nassau County: Risk Index rating Relatively High (score 92.7 of 100). Expected Annual Loss $9.9 million a year (rating Relatively High). Annualized frequency 0.52 event-days per year, from recorded occurrences over a period of record of 18 years. FEMA National Risk Index
  20. FEMA National Risk Index (version 1.20, December 2025), tornado in Nassau County: Risk Index rating Relatively Moderate (score 76.2 of 100). Expected Annual Loss $3.7 million a year (rating Relatively Moderate). Annualized frequency 0.13 events per year, from recorded occurrences over a period of record of 38 years. FEMA National Risk Index
  21. FEMA National Risk Index (version 1.20, December 2025), landslide in Nassau County: Risk Index rating Relatively Low (score 75.8 of 100). Expected Annual Loss $11,000 a year (rating Relatively Low). FEMA National Risk Index
  22. FEMA National Risk Index (version 1.20, December 2025), wildfire in Nassau County: Risk Index rating Very Low (score 43.6 of 100). Expected Annual Loss $36,000 a year (rating Very Low). FEMA's modeled annual frequency is 0.0001 events per year. FEMA National Risk Index
  23. FEMA National Risk Index (version 1.20, December 2025), hail in Nassau County: Risk Index rating Very Low (score 23.3 of 100). Expected Annual Loss $96,000 a year (rating Very Low). Annualized frequency 1.67 events per year, from recorded occurrences over a period of record of 37 years. FEMA National Risk Index
  24. FEMA National Risk Index (version 1.20, December 2025), drought in Nassau County: Risk Index rating Very Low (score 17.4 of 100). Expected Annual Loss $2,412 a year (rating Very Low). Annualized frequency 0.81 event-days per year, from recorded occurrences over a period of record of 22 years. FEMA National Risk Index
  25. FEMA National Risk Index (version 1.20, December 2025) rates these hazards Not Applicable for Nassau County: avalanche, volcanic activity. FEMA uses Not Applicable when its source data has no historical record of the hazard in the community and the hazard is not considered geographically possible there. FEMA National Risk Index documentation
  26. NFIP Residential Penetration Rates (OpenFEMA, as of 2026-08-03): 35,824 residential flood insurance contracts were in force in Nassau County, out of 371,341 residential structures, a penetration rate of 9.7%. Inside FEMA's mapped Special Flood Hazard Area there were 35,643 residential structures and 27,164... OpenFEMA NFIP penetration rates
  27. FEMA's Flood Map Service Center is the official public source for flood maps (Flood Insurance Rate Maps) produced under the National Flood Insurance Program. Flood zones apply to specific properties: look up an address there or ask the local floodplain manager. County-level ratings do not tell you the flood zone of... FEMA Flood Map Service Center
  28. Most recent federal disaster declarations for natural hazards (table on this page). OpenFEMA Disaster Declarations

FEMA's National Risk Index compares each county with all other US counties. Ratings are relative (Very Low to Very High), not a measure of safety. Never call a place safe, unsafe, good or bad to live in. Risk Index and Expected Annual Loss values are FEMA estimates for planning. They do not predict next year's losses and do not apply to a single property. Flood zones are set by FEMA flood maps for specific properties. County ratings and flood insurance counts do not tell anyone whether an address is in a flood zone. Disaster declaration, NFIP and tornado counts are records of the past for this county only. Do not compare with other counties unless a fact does.

Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties, v1.20 (December 2025). Retrieved from fema.maps.arcgis.com on October 30, 2026. This product uses the Federal Emergency Management Agency's National Risk Index dataset API or downloadable datasets 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). This product uses the FEMA OpenFEMA API, but is not endorsed by FEMA.