Nantucket County
Massachusetts — Natural Disaster Risk Assessment
Very LowComposite Risk Score
National percentile: 39th
Nantucket County faces very low composite natural disaster risk (NRI Risk Index score 38.7, 39th national percentile), driven primarily by hurricane and coastal flood exposure. Expected annual loss across all 18 hazard types is $23M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Top Hazards
All 18 Hazard Risks
| Hurricane | Medium | 0.20 / yr | $17M |
| Coastal Flood | Medium | 3.69 / yr | $2M |
| Earthquake | Very Low | 0.00 / yr | $65K |
| Drought | Very Low | 1.11 / yr | $12K |
| Riverine Flood | Very Low | 0.25 / yr | $4M |
| Wildfire | Very Low | 0.00 / yr | $8K |
| Lightning | Very Low | 14.42 / yr | $36K |
| Cold Wave | Very Low | 0.32 / yr | $16K |
| Tornado | Very Low | 0.01 / yr | $25K |
| Hail | Very Low | 0.17 / yr | $17K |
| Landslide | Very Low | 0.01 / yr | $4 |
| Strong Wind | Very Low | 0.08 / yr | $17K |
| Winter Weather | Very Low | 5.84 / yr | $2K |
| Ice Storm | Very Low | 0.01 / yr | $162 |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Heat Wave | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Frequently Asked Questions
What is the overall natural disaster risk for Nantucket County?
Nantucket County has a composite FEMA National Risk Index score of 38.7 out of 100, placing it in the Very Low category and the 39th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Nantucket County?
The three highest-rated hazards are Hurricane (Medium, $17M EAL), Coastal Flood (Medium, $2M EAL), Earthquake (Very Low, $65K EAL). These account for most of the county's expected annual losses.
How does Nantucket County compare to other Massachusetts counties?
Nantucket County ranks #13 of 14 Massachusetts counties for overall natural disaster risk, with a very low rating.
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. Nantucket County's $23M EAL is a statistical average, not a guarantee for any specific year or address.