riskbycounty
FEMA NRI 1.19.0Updated Nov 2023 · Coverage 2014–2023Methodology

Nassau County Disaster Risk

Nassau County, New York

FEMA Risk Rating

Relatively High

National Percentile

97th

of 3,144 counties

State Rank

#7

of 62 (1 = highest risk)

Flood Risk

98th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Relatively High

Higher than 98% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Relatively Low

Higher than 44% of US counties

Tornado

Tornado and severe thunderstorm risk

Relatively Low

Higher than 76% of US counties

Earthquake

Seismic activity and ground shaking risk

Relatively High

Higher than 96% of US counties

Hurricane

Tropical cyclone and hurricane risk

Relatively High

Higher than 95% of US counties

Risk Overview

About Natural Disaster Risk in Nassau County, New York

Nassau County faces very high national disaster risk

With a composite risk score of 97.14, Nassau County ranks as Relatively High—among the nation's top 5% most disaster-exposed counties. Its Long Island barrier island geography and dense suburban development create compounding vulnerabilities across nearly every hazard type.

Second-highest disaster risk in New York State

At 97.14, Nassau County ranks as one of only two counties exceeding 97 on the state scale, trailing only New York County (98.79). Its exposure vastly exceeds the state average of 69.42—a 28-point gap that reflects unique coastal and seismic vulnerabilities.

Comparable to New York County; far higher than upstate

Nassau County (97.14) mirrors the extreme risk profile of adjacent New York County (98.79) while dwarfing all upstate counties. This coastal-urban concentration of risk creates a distinct disaster landscape from the state's interior regions.

Flooding, earthquakes, and hurricanes converge here

Flood risk (98.40), earthquake risk (96.47), and hurricane risk (95.41) all reach near-maximum levels in Nassau County, while tornado risk (76.21) adds significant secondary exposure. This convergence of four major hazards makes Nassau one of America's most complex disaster zones.

Comprehensive multi-hazard insurance is mandatory

Flood insurance, earthquake coverage, wind/hail protection, and an umbrella liability policy should form the baseline in Nassau County. Review coverage annually given rising sea levels and flood zone remapping; consider elevated or reinforced foundation upgrades if you're rebuilding.

Source: FEMA National Risk Index · Narrative reviewed by Evan Brooks, Data Editor

Preparedness Guide

What to Prepare for in Nassau County

Top Hazards by Exposure

  1. #1
    FloodPrepare
    98th percentile
  2. #2
    EarthquakePrepare
    96th percentile
  3. #3
    HurricanePrepare
    95th percentile

Source: FEMA National Risk Index v1.19.0 · Percentiles are national (3,144 counties)

Local Resources

Risk Advisory: Nassau County

Risk Verdict

Nassau County ranks in the top tier for natural disaster risk nationally, with a composite score at the 97th percentile. Comprehensive household preparedness — including reviewing insurance, maintaining emergency supplies, and knowing evacuation routes — is strongly recommended.

Hazard Breakdown

Flood risk is Nassau County's dominant natural hazard, ranked at the 98th percentile nationally under FEMA's National Risk Index. Earthquake ranks second at the 96th percentile nationally. Additional tracked hazards include hurricane (95th percentile), tornado (76th percentile), wildfire (44th percentile).

Preparedness Context

Nassau County sits at the 98th percentile nationally for flood exposure. Knowing your property's flood zone designation — available at FEMA's Flood Map Service Center — is the first step toward understanding actual exposure and insurance options. Secondary earthquake exposure at the 96th percentile adds a second preparedness layer; households should review coverage options and alert sign-up for both hazard types. Regardless of specific hazard, Nassau County households benefit from a practiced communication plan: a designated out-of-state contact and a pre-agreed evacuation destination established before the season's peak risk period.

Regional Context

Compared to other New York counties, Nassau County runs 27.7 composite risk points higher than the state mean — reflecting above-average hazard concentration in this area.

Is your household prepared for Nassau County's hazards?

Review FEMA's county-specific preparedness checklists and emergency planning guides.

FEMA Ready Guide →

Frequently Asked Questions

What is the natural disaster risk in Nassau County, NY?
Nassau County has a FEMA National Risk Index rating of Relatively High, placing it in the 97th percentile nationally out of 3,144 counties. This composite score reflects the county's overall exposure to natural hazards including floods, wildfires, tornadoes, earthquakes, and hurricanes, weighted by expected annual loss and social vulnerability.
What types of natural hazards affect Nassau County?
Nassau County is evaluated for five major natural hazard types: flooding (98th percentile), earthquake (96th percentile), hurricane (95th percentile), tornado (76th percentile), wildfire (44th percentile). The highest-risk hazard is flooding at the 98th percentile nationally. These scores are derived from FEMA's National Risk Index, which analyzes expected annual loss, social vulnerability, and community resilience for each hazard type.
How does Nassau County risk compare to the New York average?
Nassau County's composite risk percentile is 97th, compared to the New York state average of 69th percentile. The state's overall risk rating is Relatively Low. This means Nassau County faces higher natural disaster risk than the typical county in New York.
Is Nassau County at risk for flooding?
Yes, Nassau County's flooding risk is at the 98th percentile nationally. This places it in the top quartile for this hazard type.
How is natural disaster risk measured?
FEMA's National Risk Index (NRI) calculates risk scores for 18 natural hazard types across all U.S. counties and census tracts. The composite score combines Expected Annual Loss (estimated dollar losses from each hazard), Social Vulnerability (demographic factors affecting disaster impact), and Community Resilience (ability to recover). Percentile scores rank each county against all 3,144 U.S. counties, and risk ratings range from Very Low to Very High.
Why is Nassau County higher risk than average?
Nassau County's composite risk score of 97th percentile is above the New York state average of 69th percentile. This elevated risk is driven by flooding exposure (98th percentile), along with earthquake and hurricane and tornado risk. Geographic location, terrain, climate patterns, and proximity to flood zones or fault lines all influence a county's risk profile.

Counties with Similar Risk

Suffolk County

New York

+0.2

Relatively High

97th percentile

Erie County

New York

+0.5

Relatively High

98th percentile

Westchester County

New York

-1.0

Relatively High

96th percentile

By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

Data Source

Risk data sourced from the FEMA National Risk Index (NRI). Risk scores are relative rankings (0–100) across all US counties — not absolute risk measures. Higher scores indicate higher relative risk compared to other counties.

Disclaimer: This data is informational only. It is not financial, insurance, or legal advice. Always consult a qualified professional before making insurance or real estate decisions.

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