Massachusetts heat wave risk
Suffolk County has the highest heat wave risk in Massachusetts, scoring 97.5 out of 100 — rated "Relatively High" by FEMA's National Risk Index. Recorded heat wave events across Massachusetts have decreased 23% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Suffolk County | 97.5 | Relatively High | 1 |
| 2 | Middlesex County | 95.7 | Relatively Moderate | 1 |
| 3 | Essex County | 91.8 | Relatively Moderate | 0 |
| 4 | Worcester County | 89.9 | Relatively Moderate | 0 |
| 5 | Hampden County | 89.7 | Relatively Moderate | 0 |
| 6 | Norfolk County | 89.6 | Relatively Moderate | 3 |
| 7 | Bristol County | 87.3 | Relatively Moderate | 0 |
| 8 | Plymouth County | 83.9 | Relatively Moderate | 1 |
| 9 | Hampshire County | 59.3 | Relatively Low | 0 |
| 10 | Franklin County | 50.7 | Relatively Low | 1 |
| 11 | Barnstable County | 38.9 | Relatively Low | 0 |
| 12 | Berkshire County | 34.9 | Very Low | 16 |
| 13 | Dukes County | 8.2 | Very Low | 0 |
| 14 | Nantucket County | 0 | No Rating | 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 Massachusetts:
Frequently asked questions
What is the highest heat wave risk county in Massachusetts?
Suffolk County, MA has the highest heat wave risk in Massachusetts, with a FEMA National Risk Index score of 97.5 out of 100 (rated "Relatively High").
What causes heat wave risk in Massachusetts?
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.