Middlesex County, Massachusetts Natural Disaster Risk
FEMA National Risk Index assessment · MA
HighComposite Risk Score
National percentile: 97th
Middlesex County faces high composite natural disaster risk (NRI Risk Index score 96.9, 97th national percentile), driven primarily by ice storm and riverine flood exposure. Expected annual loss across all 18 hazard types is $322M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
Middlesex County carries a high composite natural disaster risk, with a National Risk Index score of 96.9 out of 100 — placing it in the 97th national percentile and in the upper tier of natural-disaster risk nationally. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
The county's risk is driven primarily by ice storm (freezing rain that coats surfaces in heavy, damaging ice) at Very High risk — $8M in expected annual loss and about 2.70 events per year; riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at High risk — $224M in expected annual loss and about 4.25 events per year; and lightning (electrical discharges from storms that ignite fires and cause casualties) at High risk — $3M in expected annual loss and about 21.62 events per year. Across all hazards, FEMA estimates $322M in expected annual loss for a population of 1.63M.
Beyond physical exposure, Middlesex County has a very low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The federal record bears this out: Middlesex County has received 35 federal disaster declarations since 1985, including 9 for severe storm events and 8 for snowstorm events. The most recent was Hurricane Lee (hurricane), declared in September 2023.
Among 14 Massachusetts counties, Middlesex County ranks #1 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Ice Storm | Very High | 2.70 / yr | $8M |
| Riverine Flood | High | 4.25 / yr | $224M |
| Lightning | High | 21.62 / yr | $3M |
| Earthquake | Medium | 0.00 / yr | $24M |
| Heat Wave | Medium | 5.70 / yr | $9M |
| Hurricane | High | 0.16 / yr | $30M |
| Strong Wind | High | 0.97 / yr | $3M |
| Cold Wave | High | 1.85 / yr | $9M |
| Tornado | Medium | 0.18 / yr | $9M |
| Drought | Medium | 7.12 / yr | $2M |
| Wildfire | Low | 0.00 / yr | $268K |
| Winter Weather | Medium | 17.15 / yr | $147K |
| Coastal Flood | Low | 6.16 / yr | $418K |
| Landslide | Very Low | 0.55 / yr | $2K |
| Hail | Very Low | 2.30 / yr | $107K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Middlesex County has received 35 federal disaster declarations since 1985, most recently Hurricane Lee in September 2023. Most frequent causes: Severe Storm (9), Snowstorm (8), Hurricane (7).
| Declared | Type | Disaster |
|---|---|---|
| September 2023 | Hurricane | Hurricane Lee |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2018 | Snowstorm | Severe Winter Storm and Snowstorm |
| April 2015 | Severe Storm | Severe Winter Storm, Snowstorm, and Flooding |
| April 2013 | Severe Storm | Severe Winter Storm, Snowstorm, and Flooding |
| April 2013 | Terrorist | Explosions |
| October 2012 | Hurricane | Hurricane Sandy |
| January 2012 | Severe Storm | Severe Storm and Snowstorm |
| November 2011 | Severe Storm | Severe Storm |
Showing the 10 most recent of 35 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Middlesex County?
Middlesex County has a composite FEMA National Risk Index score of 96.9 out of 100, placing it in the High category and the 97th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Middlesex County?
The three highest-rated hazards are Ice Storm (Very High, $8M EAL), Riverine Flood (High, $224M EAL), Lightning (High, $3M EAL). These account for most of the county's expected annual losses.
How does Middlesex County compare to other Massachusetts counties?
Middlesex County ranks #1 of 14 Massachusetts counties for overall natural disaster risk, with a high rating.
How many federally declared disasters has Middlesex County had?
FEMA records 35 federal disaster declarations for Middlesex County since 1985, most often 9 for severe storm events and 8 for snowstorm events. The most recent was Hurricane Lee, declared in September 2023.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Middlesex County's $322M EAL is a statistical average, not a guarantee for any specific year or address.