New Hampshire tornado risk
Hillsborough County has the highest tornado risk in New Hampshire, scoring 82.6 out of 100 — rated "Relatively Moderate" by FEMA's National Risk Index.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Hillsborough County | 82.6 | Relatively Moderate | 0 |
| 2 | Rockingham County | 73.5 | Relatively Moderate | 0 |
| 3 | Merrimack County | 56.2 | Relatively Low | 1 |
| 4 | Cheshire County | 43.6 | Relatively Low | 4 |
| 5 | Strafford County | 42.2 | Relatively Low | 0 |
| 6 | Belknap County | 31.4 | Relatively Low | 1 |
| 7 | Grafton County | 24.4 | Very Low | 3 |
| 8 | Sullivan County | 22.7 | Very Low | 2 |
| 9 | Carroll County | 18.9 | Very Low | 1 |
| 10 | Coos County | 10.6 | Very Low | 1 |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Tornado risk nationally:
Other hazard risks in New Hampshire:
Frequently asked questions
What is the highest tornado risk county in New Hampshire?
Hillsborough County, NH has the highest tornado risk in New Hampshire, with a FEMA National Risk Index score of 82.6 out of 100 (rated "Relatively Moderate").
What causes tornado risk in New Hampshire?
Tornado risk concentrates in the central and southern plains ("Tornado Alley") and the Southeast ("Dixie Alley"), where atmospheric conditions favor supercell thunderstorm development. The highest scores often belong to counties with significant mobile home and manufactured housing stock, which carries disproportionate tornado mortality risk.