New Hampshire heat wave risk
Hillsborough County has the highest heat wave risk in New Hampshire, scoring 75.4 out of 100 — rated "Relatively Low" by FEMA's National Risk Index.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Hillsborough County | 75.4 | Relatively Low | 1 |
| 2 | Merrimack County | 70.6 | Relatively Low | 1 |
| 3 | Rockingham County | 65 | Relatively Low | 1 |
| 4 | Cheshire County | 51.6 | Relatively Low | 0 |
| 5 | Strafford County | 49.4 | Relatively Low | 1 |
| 6 | Sullivan County | 44.5 | Relatively Low | 0 |
| 7 | Grafton County | 44.3 | Relatively Low | 0 |
| 8 | Belknap County | 42.5 | Relatively Low | 0 |
| 9 | Carroll County | 34.2 | Very Low | 1 |
| 10 | Coos County | 12.7 | Very Low | 0 |
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.
Heat Wave risk nationally:
Other hazard risks in New Hampshire:
Frequently asked questions
What is the highest heat wave risk county in New Hampshire?
Hillsborough County, NH has the highest heat wave risk in New Hampshire, with a FEMA National Risk Index score of 75.4 out of 100 (rated "Relatively Low").
What causes heat wave risk in New Hampshire?
Heat is consistently the leading cause of weather-related mortality in the US, yet it remains underrepresented in federal disaster declarations relative to its actual impact. High scores reflect a combination of extreme temperature exposure, population vulnerability (elderly, outdoor workers), and limited access to cooling infrastructure.