Nassau County, New York Natural Disaster Risk
FEMA National Risk Index assessment · NY
HighComposite Risk Score
National percentile: 97th
Nassau County faces high composite natural disaster risk (NRI Risk Index score 97.1, 97th national percentile), driven primarily by winter weather and ice storm exposure. Expected annual loss across all 18 hazard types is $299M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Overall natural disaster risk in Nassau County is high, with a National Risk Index score of 97.1 out of 100 — placing it in the 97th national percentile and in the upper tier of natural-disaster risk nationally. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Nassau County's expected losses come from winter weather (heavy snow, blizzards, and hazardous winter conditions) at Very High risk — $2M in expected annual loss and about 9.75 events per year; ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Very High risk — $4M in expected annual loss and about 0.72 events per year; and coastal flood (seawater inundation from storm surge, high tides, and rising sea levels) at Very High risk — $24M in expected annual loss and about 3.83 events per year. Across all hazards, FEMA estimates $299M in expected annual loss for a population of 1.4M.
Beyond physical exposure, Nassau County has a low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The county's disaster history tells the same story: Nassau County has received 31 federal disaster declarations since 1965, including 12 for hurricane events and 6 for severe storm events. The most recent was Severe Storm and Flooding (flood), declared in January 2024.
Among 62 New York counties, Nassau County ranks #7 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Winter Weather | Very High | 9.75 / yr | $2M |
| Ice Storm | Very High | 0.72 / yr | $4M |
| Coastal Flood | Very High | 3.83 / yr | $24M |
| Riverine Flood | High | 3.29 / yr | $184M |
| Lightning | Very High | 27.27 / yr | $3M |
| Strong Wind | High | 4.87 / yr | $4M |
| Earthquake | Medium | 0.00 / yr | $28M |
| Heat Wave | Medium | 5.82 / yr | $8M |
| Hurricane | High | 0.17 / yr | $27M |
| Cold Wave | High | 0.52 / yr | $10M |
| Tornado | Medium | 0.13 / yr | $4M |
| Landslide | Low | 0.08 / yr | $11K |
| Wildfire | Very Low | 0.00 / yr | $36K |
| Hail | Very Low | 1.67 / yr | $96K |
| Drought | Very Low | 0.81 / yr | $2K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Nassau County has received 31 federal disaster declarations since 1965, most recently Severe Storm and Flooding in January 2024. Most frequent causes: Hurricane (12), Severe Storm (6), Flood (4).
| Declared | Type | Disaster |
|---|---|---|
| January 2024 | Flood | Severe Storm and Flooding |
| September 2021 | Hurricane | Remnants of Hurricane Ida |
| September 2021 | Hurricane | Remnants of Hurricane Ida |
| August 2021 | Hurricane | Hurricane Henri |
| October 2020 | Hurricane | Tropical Storm Isaias |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| October 2012 | Hurricane | Hurricane Sandy |
| October 2012 | Hurricane | Hurricane Sandy |
| August 2011 | Hurricane | Hurricane Irene |
Showing the 10 most recent of 31 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Nassau County?
Nassau County has a composite FEMA National Risk Index score of 97.1 out of 100, placing it in the High category and the 97th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Nassau County?
The three highest-rated hazards are Winter Weather (Very High, $2M EAL), Ice Storm (Very High, $4M EAL), Coastal Flood (Very High, $24M EAL). These account for most of the county's expected annual losses.
How does Nassau County compare to other New York counties?
Nassau County ranks #7 of 62 New York counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Nassau County had?
FEMA records 31 federal disaster declarations for Nassau County since 1965, most often 12 for hurricane events and 6 for severe storm events. The most recent was Severe Storm and Flooding, declared in January 2024.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Nassau County's $299M EAL is a statistical average, not a guarantee for any specific year or address.