Nantucket County Disaster Risk

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.

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.

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.

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.

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.

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.