Norfolk County, Massachusetts Natural Disaster Risk
FEMA National Risk Index assessment · MA
MediumComposite Risk Score
National percentile: 92th
Norfolk County faces medium composite natural disaster risk (NRI Risk Index score 92.0, 92th national percentile), driven primarily by riverine flood and hurricane exposure. Expected annual loss across all 18 hazard types is $147M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Norfolk County at medium composite risk, with a National Risk Index score of 92.0 out of 100 — placing it in the 92nd national percentile and near the national midpoint for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Norfolk County's expected losses come from riverine flood (rivers and streams overflowing their banks after heavy rain or snowmelt) at High risk — $103M in expected annual loss and about 2.86 events per year; hurricane (tropical cyclones bringing extreme wind, rain, and storm surge) at Medium risk — $16M in expected annual loss and about 0.18 events per year; and earthquake (ground shaking from sudden movement along geologic faults) at Medium risk — $9M in expected annual loss and about 0.00 events per year. Across all hazards, FEMA estimates $147M in expected annual loss for a population of 726K.
Beyond physical exposure, Norfolk 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: Norfolk County has received 38 federal disaster declarations since 1972, including 9 for snowstorm events and 8 for hurricane events. The most recent was Hurricane Lee (hurricane), declared in September 2023.
Among 14 Massachusetts counties, Norfolk County ranks #6 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Riverine Flood | High | 2.86 / yr | $103M |
| Hurricane | Medium | 0.18 / yr | $16M |
| Earthquake | Medium | 0.00 / yr | $9M |
| Ice Storm | High | 1.78 / yr | $1M |
| Heat Wave | Medium | 6.07 / yr | $4M |
| Lightning | High | 20.99 / yr | $1M |
| Coastal Flood | High | 7.92 / yr | $5M |
| Cold Wave | Medium | 1.30 / yr | $3M |
| Landslide | Low | 0.23 / yr | $9K |
| Tornado | Medium | 0.08 / yr | $3M |
| Strong Wind | Medium | 0.92 / yr | $1M |
| Wildfire | Very Low | 0.00 / yr | $61K |
| Winter Weather | Low | 12.98 / yr | $81K |
| Drought | Low | 5.77 / yr | $98K |
| Hail | Very Low | 1.84 / yr | $43K |
| Avalanche | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Norfolk County has received 38 federal disaster declarations since 1972, most recently Hurricane Lee in September 2023. Most frequent causes: Snowstorm (9), Hurricane (8), Severe Storm (7).
| Declared | Type | Disaster |
|---|---|---|
| September 2023 | Hurricane | Hurricane Lee |
| April 2022 | Snowstorm | Severe Winter Storm and Snowstorm |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2018 | Snowstorm | Severe Winter Storm and Snowstorm |
| June 2018 | Severe Storm | Severe Winter Storm and Flooding |
| 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 |
Showing the 10 most recent of 38 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Norfolk County?
Norfolk County has a composite FEMA National Risk Index score of 92.0 out of 100, placing it in the Medium category and the 92th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Norfolk County?
The three highest-rated hazards are Riverine Flood (High, $103M EAL), Hurricane (Medium, $16M EAL), Earthquake (Medium, $9M EAL). These account for most of the county's expected annual losses.
How does Norfolk County compare to other Massachusetts counties?
Norfolk County ranks #6 of 14 Massachusetts counties for overall natural disaster risk, with a medium rating.
How many federally declared disasters has Norfolk County had?
FEMA records 38 federal disaster declarations for Norfolk County since 1972, most often 9 for snowstorm events and 8 for hurricane 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. Norfolk County's $147M EAL is a statistical average, not a guarantee for any specific year or address.