Nassau County, New York: Natural Disaster Risk and History
Nassau County, New York has a Relatively High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 97.1 out of 100, higher than about 97% of US counties, with winter storms, ice storms and coastal flooding scoring highest of its 18 hazards and $299 million a year in expected losses.
OpenFEMA lists 29 federal disaster declarations that included Nassau County since 1965, not counting 2 for COVID-19; the latest is DR-4755-NY (Severe Storm and Flooding, declared 30 January 2024). NOAA's Storm Prediction Center recorded 9 tornadoes touching Nassau County from 1950 to 2025.
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Population 1,395,584 Buildings worth $303 billion Area 458 sq mi Risk rank in New York 7 of 62 FIPS 36059
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Winter weather | Very High | 98.9 | $2.0 million | about 9.8 a year | 122 |
| Ice storm | Very High | 98.7 | $3.9 million | about once every 1.4 years | 38 |
| Coastal flooding | Very High | 98.4 | $24 million | about 3.8 a year | — |
| Inland flooding | Relatively High | 98.2 | $184 million | about 3.3 a year | 92 |
| Lightning | Very High | 97.3 | $3.0 million | about 27 a year | 560,320 strikes |
| Strong wind | Relatively High | 97.1 | $4.5 million | about 4.9 a year | 142 |
| Earthquake | Relatively Moderate | 96.5 | $28 million | about once every 529 years | — |
| Heat wave | Relatively Moderate | 96.0 | $8.3 million | about 5.8 a year | 63 |
| Hurricane | Relatively High | 95.4 | $27 million | about once every 5.8 years | 56 |
| Cold wave | Relatively High | 92.7 | $9.9 million | about once every 1.9 years | 6.4 |
| Tornado | Relatively Moderate | 76.2 | $3.7 million | about once every 7.9 years | 8 |
| Landslide | Relatively Low | 75.9 | $11,436 | about once every 13 years | — |
| Wildfire | Very Low | 43.6 | $36,149 | rarer than once in 1,000 years | — |
| Hail | Very Low | 23.4 | $95,846 | about 1.7 a year | 73 |
| Drought | Very Low | 17.5 | $2,412 | about once every 1.2 years | 21 |
| Avalanche | Not Applicable | — | — | — | — |
| Tsunami | Insufficient Data | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 29
Most common: Hurricane 12, Severe Storm 6, Flood 4, Snowstorm 3.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 1 | Drought |
| 1970s | 2 | Hurricane, Flood |
| 1980s | 2 | Hurricane, Flood |
| 1990s | 6 | Severe Storm ×2, Snowstorm ×2, Hurricane, Flood |
| 2000s | 7 | Severe Storm ×2, Other ×2, Hurricane, Snowstorm, Fire |
| 2010s | 6 | Hurricane ×4, Severe Storm ×2 |
| 2020s | 5 | Hurricane ×4, Flood |
The last 10
Widest declarations that included Nassau County
- Hurricane Sandy (2012, EM-3351-NY): 62 New York counties designated.
- Hurricane Katrina Evacuation (2005, EM-3262-NY): 62 New York counties designated.
- Severe Storms and Flooding (2004, DR-1534-NY): 62 New York counties designated.
Named storms in its declarations: Hurricane Ida (2021), Hurricane Henri (2021), Tropical Storm Isaias (2020), Hurricane Sandy (2012), Hurricane Irene (2011), Hurricane Katrina (2005), Hurricane Floyd (1999), Hurricane Gloria (1985), Hurricane Belle (1976).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. New York also had 7 statewide declarations with no county list.
Tornado record since 1950 9
| Tornadoes touching the county | 9 |
|---|---|
| Strongest-rated | (E)F2 ×3 |
| Peak month | August (3) |
| Deadliest | 7 Sep 1998, F2, 0.2 mi path, 0 killed, 6 injured |
| Longest path | 13 Nov 2021, EF0, 13.1 mi path |
| Most recent | 13 Nov 2021, EF0, 13.1 mi path |
| Deaths / injuries on those paths | 0 / 6 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 3 | 3 | 3 | 0 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 0 | 0 | 4 | 0 | 2 | 2 | 0 | 1 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Nassau County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Nassau County (this page) | — | Relatively High | 97.1 | Winter weather |
| Queens County | 20 km | Relatively High | 99.2 | Cold wave |
| Bronx County | 26 km | Relatively High | 98.3 | Cold wave |
| New York County | 32 km | Relatively High | 98.8 | Heat wave |
| Kings County | 32 km | Relatively High | 99.3 | Winter weather |
| Hudson County, NJ | 41 km | Relatively High | 97.2 | Heat wave |
Nearest by distance between county centres. Every county in New York, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively Low 25.9 |
|---|---|
| Community resilience | Very High 97.0 |
| Community risk factor | 0.93 |
| Expected annual loss, all hazards | $299 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Nassau County's main hazards
- Right now: National Weather Service alerts for New York · all official warnings on Global Incident Tracker.
- Winter weather: Power outages now · Carbon monoxide in winter
- Ice storm: Power outages now · Carbon monoxide in winter
- Coastal flooding: Flood safety: why shallow water kills · Hurricanes and storms now
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. 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).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. 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).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Nassau County
What natural disasters is Nassau County, New York most at risk from?
Nassau County, New York has a Relatively High natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 97.1 out of 100, higher than about 97% of US counties, with winter storms, ice storms and coastal flooding scoring highest of its 18 hazards and $299 million a year in expected losses.
How many federal disaster declarations has Nassau County had?
OpenFEMA lists 29 federal disaster declarations that included Nassau County since 1965, not counting 2 for COVID-19; the latest is DR-4755-NY (Severe Storm and Flooding, declared 30 January 2024). Another 7 New York declarations were made statewide without a county list.
How many tornadoes have hit Nassau County?
NOAA's Storm Prediction Center recorded 9 tornadoes touching Nassau County from 1950 to 2025. The deadliest: 7 Sep 1998, F2, 0.2 mi path, 0 killed, 6 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.