Natural disaster risk in New Hampshire, by county
All 10 counties in New Hampshire, ranked by FEMA's National Risk Index composite risk score, with each one's highest-rated hazard. Other states
At a glance
Highest overall risk: Hillsborough County (relatively moderate, score 89.8). Lowest: Sullivan County (very low, score 37.6).
Top hazards in New Hampshire
| Hazard | Counties rated relatively high or very high | Average score |
|---|---|---|
| Ice storm | 6 of 10 | 81.9 |
| Winter weather | 4 of 10 | 72.3 |
| Lightning | 3 of 10 | 75.2 |
| Coastal flooding | 1 of 10 | 68.0 |
| Strong wind | 1 of 10 | 43.5 |
All counties, highest risk first
| # | County | Overall risk | Highest-rated hazard |
|---|---|---|---|
| 1 | Hillsborough County | Relatively moderate 89.8 | Ice storm (very high) |
| 2 | Rockingham County | Relatively moderate 85.8 | Coastal flooding (relatively high) |
| 3 | Grafton County | Relatively moderate 81.8 | Winter weather (relatively high) |
| 4 | Merrimack County | Relatively low 78.2 | Ice storm (relatively high) |
| 5 | Coos County | Relatively low 72.8 | Avalanche (very high) |
| 6 | Carroll County | Relatively low 71 | Winter weather (relatively high) |
| 7 | Strafford County | Relatively low 64.1 | Ice storm (relatively high) |
| 8 | Cheshire County | Relatively low 60.5 | Lightning (relatively moderate) |
| 9 | Belknap County | Relatively low 57.4 | Lightning (relatively high) |
| 10 | Sullivan County | Very low 37.6 | Ice storm (relatively moderate) |
How to read these ratings
- Ratings run in five steps: very low, relatively low, relatively moderate, relatively high and very high. They compare a county with every other US county; they are not a measure of danger on their own.
- Scores run from 0 to 100 and are national percentiles. The bar shows the score: a score of 80 means a higher value than 80% of US counties.
- Overall risk combines the expected annual loss with social vulnerability and community resilience.
- Expected annual loss is the average yearly loss to buildings, people and agriculture the model expects from all 18 hazards.
- Social vulnerability describes how hard it may be for people to prepare for and recover from a disaster. Higher is worse.
- Community resilience describes a community's ability to prepare, adapt and recover. Higher is better.
- "Not applicable" means FEMA does not model that hazard there (for example, hurricanes far inland).
About this data
Source: FEMA National Risk Index, version 1.20, released December 2025, published by the Federal Emergency Management Agency (US public domain). About the National Risk Index. The index is a model of relative risk built from historical hazard records, what is exposed and community factors. It is not a forecast, it does not describe any single property, and it is not insurance or financial advice. For decisions about a specific address, check FEMA's flood maps and your local emergency management office.
Questions
Which county in New Hampshire has the highest natural disaster risk?
Hillsborough County has the highest composite risk score in New Hampshire in FEMA's National Risk Index: 89.8, rated relatively moderate.
Which county in New Hampshire has the lowest natural disaster risk?
Sullivan County has the lowest composite risk score in New Hampshire: 37.6, rated very low. A low score means lower modelled risk compared with other US counties, not no risk.
What natural disasters is New Hampshire most at risk from?
Across New Hampshire, the hazards rated highest in the most counties are ice storm, winter weather, lightning, according to FEMA's National Risk Index. Each county page lists all 18 hazards.
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