Boston survival atlas
Suffolk County, Massachusetts
Boston’s biggest natural hazards are inland flooding, hurricanes and earthquakes. In FEMA’s National Risk Index they make up 73% of the natural-hazard risk for Suffolk County, home to all of Boston’s 672,973 residents. FEMA rates the county’s overall risk Relatively Moderate. Here is what to do for each, step by step.
- People
- 672,973 Census estimate, July 1, 2025. No. 25 in the U.S.
- County
- Suffolk County All of Boston’s residents. FEMA rates counties, not cities.
- Overall risk
- Relatively Moderate Score 93.51 of 100. No. 30 of the 30 largest U.S. cities.
- Expected loss
- $115 million A year, from all 18 natural hazards (FEMA estimate).
- Top 3 hazards
- 73% of the county’s risk comes from these three: Inland flooding · Hurricane · Earthquake.
What to do for Boston’s top hazards
The one rule to remember, then the first steps, word for word from our guides. Each guide lists its sources.
Inland flooding
FEMA score 94.72: higher than 94.7% of U.S. counties. Expected loss $59.5 million a year.
- Get to high ground now.
- Never walk, swim or drive into floodwater. 6 inches of moving water can knock you down; 12 inches carries away most cars.
- Car stalls in rising water: get out to higher ground if you safely can. Trapped in fast water: stay inside; if water rises inside, get on the roof.
Hurricane
FEMA score 93.65: higher than 93.6% of U.S. counties. Expected loss $12.9 million a year.
- Know if you live in an evacuation zone before the season starts.
- If you're told to evacuate, go. Early.
- If you stay inland, shelter in a small interior room away from windows.
Earthquake
FEMA score 94.97: higher than 94.9% of U.S. counties. Expected loss $11.7 million a year.
- Drop to your hands and knees.
- Cover your head and neck, under a sturdy table if one is close.
- Hold on until the shaking stops. Don't run outside or stand in a doorway.
All 18 natural hazards in Boston, ranked
Ranked by each hazard’s share of Suffolk County’s risk in FEMA’s National Risk Index. The score compares the county with every other U.S. county for that one hazard.
| # | Hazard | Share of risk | FEMA rating | Score | Expected loss a year | The rule |
|---|---|---|---|---|---|---|
| 1 | Inland flooding | 52% | Relatively High | 94.72 | $59.5 million | Turn around, don't drown. |
| 2 | Hurricane | 11% | Relatively High | 93.65 | $12.9 million | Know your evacuation zone. Told to go? Go early. |
| 3 | Earthquake | 10% | Relatively Moderate | 94.97 | $11.7 million | Drop. Cover. Hold on. |
| 4 | Heat wave | 8.2% | Relatively High | 97.46 | $9.4 million | Get somewhere cool. Check on anyone who lives alone. |
| 5 | Cold wave | 7.6% | Relatively High | 94.17 | $8.7 million | One warm room. Never heat with an oven or a grill. |
| 6 | Coastal flooding | 5.5% | Relatively High | 92.20 | $6.3 million | Run from the water. Hide from the wind. |
| 7 | Tornado | 2.3% | Relatively Moderate | 75.34 | $2.6 million | Lowest floor, interior room, cover your head. |
| 8 | Lightning | 2.0% | Very High | 97.77 | $2.3 million | When thunder roars, go indoors. |
| 9 | Hail | 0.5% | Relatively Moderate | 76.94 | $615,000 | Large hail coming? Get inside a sturdy building and away from the windows. |
| 10 | Strong wind | 0.4% | Relatively Moderate | 52.03 | $480,000 | Shelter in an interior room, away from windows. |
| 11 | Ice storm | 0.3% | Relatively Moderate | 79.87 | $329,000 | Stay off the roads. One warm room. |
| 12 | Winter weather | <0.1% | Relatively Low | 44.14 | $43,000 | Stay in your shelter, or stay with your car. |
| 13 | Wildfire | <0.1% | Very Low | 8.96 | $2,000 | Leave early. Know two ways out. |
| 14 | Landslide | <0.1% | Very Low | 36.22 | $406 | Follow local alerts. Leave when officials say so. |
| – | Avalanche | – | Not applicable | – | – | Check your local avalanche center before backcountry travel. |
| – | Drought | – | No rating | – | – | Store water now: 1 gallon per person per day. |
| – | Tsunami | – | Insufficient data | – | – | Strong or long shaking near the sea: go high now. |
| – | Volcanic activity | – | Not applicable | – | – | Evacuate early. In ashfall, stay in and wear an N95. |
Source // FEMA National Risk Index v1.20 (December 2025), county 25025. Rules: SOS.city survival guides.
How to read these numbers
- Share of risk. For each hazard, FEMA estimates the loss each year to buildings, people and farms, then adjusts it for social vulnerability and community resilience. The county’s overall risk is the sum of all 18, so the share shows how much of it each hazard carries.
- Score. A percentile from 0 to 100. A score of 99.5 means the county’s risk for that hazard is higher than 99.5% of U.S. counties.
- Rating. FEMA sorts counties into five groups, from Very Low to Very High.
- Big places rank high. Expected losses grow with the number of people and buildings exposed, so large urban counties rank high on many hazards. A high rating means plan for it, not that it will happen this year.
- County, not street. These ratings cover the whole county. For flood risk at your address, look it up on the FEMA Flood Map Service Center.
- Suffolk County is rated Relatively High for social vulnerability and Very High for community resilience. Both feed into its overall rating.
Questions people ask
What natural disasters is Boston most at risk for?
Boston’s biggest natural hazards are inland flooding, hurricanes and earthquakes. In FEMA’s National Risk Index they make up 73% of the natural-hazard risk for Suffolk County, home to all of Boston’s 672,973 residents. FEMA rates the county’s overall risk Relatively Moderate.
How does FEMA rate Boston’s overall disaster risk?
FEMA’s National Risk Index rates the overall risk of Suffolk County Relatively Moderate, with a score of 93.51 out of 100. The score is a percentile: Suffolk County’s overall risk is higher than 93.5% of U.S. counties. Expected losses from natural hazards there average $115 million a year.
What should I do first to get ready in Boston?
Write down your top three: inland flooding, hurricanes and earthquakes. Turn on Emergency Alerts on every phone and sign up for your county’s alerts. Store water: 1 gallon per person per day for at least 3 days, 2 weeks if you can.
Sources
Every number on this page comes from these public datasets. We check them when we review the page.
- FEMA: National Risk Index data, county table (v1.20, December 2025)
- FEMA: National Risk Index frequently asked questions (December 2025)
- FEMA: National Risk Index for Natural Hazards
- U.S. Census Bureau: City and town population totals, 2020–2025 (Vintage 2025)
- Steps: What to do in a flood or flash flood (SOS.city guide; its sources are listed on the page)
- Steps: What to do in a hurricane (SOS.city guide; its sources are listed on the page)
- Steps: What to do during an earthquake (SOS.city guide; its sources are listed on the page)
General safety information, not medical advice. In an emergency, call 911 and follow local officials.
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