Houston survival atlas
Harris County, Texas
Houston’s biggest natural hazards are inland flooding, hurricanes and tornadoes. In FEMA’s National Risk Index they make up 89% of the natural-hazard risk for Harris County, home to 98% of Houston’s 2.4 million residents. FEMA rates the county’s overall risk Very High. Here is what to do for each, step by step.
- People
- 2,397,315 Census estimate, July 1, 2025. No. 4 in the U.S.
- County
- Harris County Home to 97.9% of Houston’s residents. FEMA rates counties, not cities.
- Overall risk
- Very High Score 99.93 of 100. No. 3 of the 10 largest U.S. cities.
- Expected loss
- $2.2 billion A year, from all 18 natural hazards (FEMA estimate).
- Top 3 hazards
- 89% of the county’s risk comes from these three: Inland flooding · Hurricane · Tornado.
What to do for Houston’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 99.96: higher than 99.9% of U.S. counties. Expected loss $1.1 billion 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 100.00: the highest of any U.S. county. Expected loss $458 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.
Tornado
FEMA score 100.00: the highest of any U.S. county. Expected loss $407 million a year.
- Go to the lowest floor: a small interior room away from windows.
- Cover your head and neck.
- In a mobile home or a car: get to a sturdy building.
All 18 natural hazards in Houston, ranked
Ranked by each hazard’s share of Harris 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 | 51% | Very High | 99.96 | $1.1 billion | Turn around, don't drown. |
| 2 | Hurricane | 21% | Very High | 100.00 | $458 million | Know your evacuation zone. Told to go? Go early. |
| 3 | Tornado | 18% | Very High | 100.00 | $407 million | Lowest floor, interior room, cover your head. |
| 4 | Cold wave | 5.3% | Very High | 99.90 | $118 million | One warm room. Never heat with an oven or a grill. |
| 5 | Heat wave | 3.6% | Very High | 99.71 | $80.4 million | Get somewhere cool. Check on anyone who lives alone. |
| 6 | Lightning | 0.4% | Very High | 99.90 | $8.6 million | When thunder roars, go indoors. |
| 7 | Strong wind | 0.3% | Very High | 99.26 | $7.7 million | Shelter in an interior room, away from windows. |
| 8 | Earthquake | 0.3% | Relatively Moderate | 92.14 | $5.9 million | Drop. Cover. Hold on. |
| 9 | Ice storm | 0.2% | Very High | 99.56 | $4.1 million | Stay off the roads. One warm room. |
| 10 | Coastal flooding | 0.1% | Relatively High | 83.20 | $2.5 million | Run from the water. Hide from the wind. |
| 11 | Hail | <0.1% | Relatively Moderate | 91.98 | $1.6 million | Get indoors, away from windows. |
| 12 | Wildfire | <0.1% | Relatively Low | 85.43 | $562,000 | Leave early. Know two ways out. |
| 13 | Drought | <0.1% | Relatively Moderate | 75.06 | $550,000 | Store water now: 1 gallon per person per day. |
| 14 | Winter weather | <0.1% | Relatively High | 88.82 | $296,000 | Stay in your shelter, or stay with your car. |
| 15 | Landslide | <0.1% | Relatively Moderate | 88.39 | $37,000 | Follow local alerts. Leave when officials say so. |
| – | Avalanche | – | Not applicable | – | – | Check your local avalanche center before backcountry travel. |
| – | 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 48201. Rules: SOS.city survival guides.
The rest of Houston
Houston also reaches into 2 other counties, which FEMA rates separately.
| County | Houston residents | Overall FEMA rating | Top 3 hazards by share of risk |
|---|---|---|---|
| Fort Bend County | 43,668 (1.8%) | Relatively High (97.45) | Inland flooding, Hurricane, Tornado |
| Montgomery County | 6,301 (0.3%) | Relatively High (95.73) | Inland flooding, Tornado, Cold wave |
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.
- Harris County is rated Relatively High for social vulnerability and Very Low for community resilience. Both feed into its overall rating.
Questions people ask
What natural disasters is Houston most at risk for?
Houston’s biggest natural hazards are inland flooding, hurricanes and tornadoes. In FEMA’s National Risk Index they make up 89% of the natural-hazard risk for Harris County, home to 98% of Houston’s 2.4 million residents. FEMA rates the county’s overall risk Very High.
How does FEMA rate Houston’s overall disaster risk?
FEMA’s National Risk Index rates the overall risk of Harris County Very High, with a score of 99.93 out of 100. The score is a percentile: Harris County’s overall risk is higher than 99.9% of U.S. counties. Expected losses from natural hazards there average $2.2 billion a year.
What should I do first to get ready in Houston?
Write down your top three: inland flooding, hurricanes and tornadoes. 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 in a tornado warning (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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