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

Nantucket County Disaster Risk

Nantucket County, Massachusetts

FEMA Risk Rating

Very Low

National Percentile

39th

of 3,144 counties

State Rank

#13

of 14 (1 = highest risk)

Flood Risk

70th

percentile

Hazard Risk Breakdown

Flood

River, coastal, and surface flooding risk

Relatively Low

Higher than 70% of US counties

Wildfire

Wildland and wildland-urban interface fire risk

Very Low

Higher than 13% of US counties

Tornado

Tornado and severe thunderstorm risk

Very Low

Higher than 4% of US counties

Earthquake

Seismic activity and ground shaking risk

Very Low

Higher than 22% of US counties

Hurricane

Tropical cyclone and hurricane risk

Moderate

Higher than 91% of US counties

Risk Overview

About Natural Disaster Risk in Nantucket County, Massachusetts

Nantucket has very low overall disaster risk

Nantucket County scores 38.68 on composite risk, placing it in the very low category—far below the national average. This score reflects minimal exposure to most natural hazards, with one notable exception.

Lowest-risk county in Massachusetts

Nantucket ranks as the safest county in Massachusetts, with a composite score of 38.68 compared to the state average of 78.84. The county's 51% reduction below the state baseline reflects exceptionally low tornado, earthquake, and wildfire risks.

Significantly safer than mainland peers

Nantucket's 38.68 score substantially trails other Massachusetts counties: Plymouth (90.36), Norfolk (92.02), and Suffolk (93.51) all exceed 90. Nantucket's isolation as an island community has created a unique low-risk profile across most hazard categories.

Hurricane exposure is your primary concern

Hurricane risk reaches 90.95 in Nantucket—among the highest in the county—reflecting the island's Atlantic exposure. Flood risk stands at 70.00, while wildfire (13.01), tornado (4.10), and earthquake (22.36) risks remain minimal.

Hurricane preparedness is your insurance priority

Standard homeowners policies typically cover hurricane wind damage, but you should verify your deductible and coverage limits given Nantucket's coastal location. Consider supplemental flood insurance, as storm surge and heavy rainfall can exceed standard policy limits even on this lower-risk island.

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

Preparedness Guide

What to Prepare for in Nantucket County

Top Hazards by Exposure

  1. #1
    HurricanePrepare
    91th percentile
  2. #2
    FloodPrepare
    70th percentile
  3. #3
    EarthquakePrepare
    22th percentile

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

Risk Advisory: Nantucket County

Risk Verdict

Nantucket County sits in the lower tier of U.S. counties for natural disaster exposure, ranked at the 39th percentile nationally. Nantucket County's 39th percentile ranking is favorable, though every county carries at least one natural hazard worth knowing — reviewing the specific risks listed above helps households focus their preparedness where it matters most.

Hazard Breakdown

Hurricane risk is Nantucket County's dominant natural hazard, ranked at the 91th percentile nationally under FEMA's National Risk Index. Flood ranks second at the 70th percentile nationally. Additional tracked hazards include earthquake (22th percentile), wildfire (13th percentile), tornado (4th percentile).

Preparedness Context

At the 91th percentile nationally for hurricane exposure, Nantucket County households benefit from reviewing both homeowners and flood insurance coverage before storm season begins — standard policies often exclude storm surge, which is the leading cause of hurricane fatalities. Flood at the 70th percentile nationally is Nantucket County's secondary hazard, often intensified by the same weather systems that produce hurricane conditions. Hurricane-force winds cause direct property damage, but storm surge causes the majority of hurricane-related deaths. Nantucket County households near tidal water or low-elevation areas should verify whether they are in a storm surge risk zone.

Regional Context

Nantucket County falls 40.2 points below Massachusetts's typical county risk level, making it one of the safer natural-hazard environments in the state.

Is your household prepared for Nantucket 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 Nantucket County, MA?
Nantucket County has a FEMA National Risk Index rating of Very Low, placing it in the 39th 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 Nantucket County?
Nantucket County is evaluated for five major natural hazard types: hurricane (91th percentile), flooding (70th percentile), earthquake (22th percentile), wildfire (13th percentile), tornado (4th percentile). The highest-risk hazard is hurricane at the 91th 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 Nantucket County risk compare to the Massachusetts average?
Nantucket County's composite risk percentile is 39th, compared to the Massachusetts state average of 79th percentile. The state's overall risk rating is Relatively Low. This means Nantucket County faces lower natural disaster risk than the typical county in Massachusetts.
Is Nantucket County at risk for hurricane?
Yes, Nantucket County's hurricane risk is at the 91th percentile nationally. This places it in the top quartile for this hazard type. For flooding specifically, Nantucket County is at the 70th percentile.
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.
Is Nantucket County a safe place to live?
Nantucket County's composite risk score of 39th percentile is below the Massachusetts state average of 79th percentile, indicating relatively lower exposure to natural hazards. However, no county is completely risk-free. The primary hazard type is hurricane at the 91th percentile. Residents should still maintain emergency preparedness plans and appropriate insurance coverage.
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.