Massachusetts inland flooding risk
Middlesex County has the highest inland flooding risk in Massachusetts, scoring 98.5 out of 100 — rated "Relatively High" by FEMA's National Risk Index. Recorded inland flooding events across Massachusetts have decreased 30% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Middlesex County | 98.5 | Relatively High | 129 |
| 2 | Essex County | 97.1 | Relatively High | 78 |
| 3 | Hampden County | 95.9 | Relatively High | 63 |
| 4 | Norfolk County | 95.5 | Relatively High | 85 |
| 5 | Worcester County | 95.3 | Relatively High | 139 |
| 6 | Suffolk County | 94.7 | Relatively High | 51 |
| 7 | Bristol County | 93.6 | Relatively High | 82 |
| 8 | Plymouth County | 92.9 | Relatively Moderate | 31 |
| 9 | Barnstable County | 90.7 | Relatively Moderate | 41 |
| 10 | Berkshire County | 90.6 | Relatively Moderate | 44 |
| 11 | Hampshire County | 79.4 | Relatively Moderate | 26 |
| 12 | Franklin County | 73.5 | Relatively Moderate | 35 |
| 13 | Dukes County | 32 | Very Low | 6 |
| 14 | Nantucket County | 16.6 | Very Low | 3 |
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.
Inland Flooding risk nationally:
Other hazard risks in Massachusetts:
Frequently asked questions
What is the highest inland flooding risk county in Massachusetts?
Middlesex County, MA has the highest inland flooding risk in Massachusetts, with a FEMA National Risk Index score of 98.5 out of 100 (rated "Relatively High").
What causes inland flooding risk in Massachusetts?
Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.