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Tornado Risk by County: Tornado Alley and Beyond
Which counties have the highest long-run tornado risk.
2 counties share the top score of 100 out of 100 on FEMA's National Risk Index: Harris County, Texas, Cook County, Illinois.
Open the live map →🌪️Highest-scoring counties
| County | Fema tornado risk score (0-100) |
|---|---|
| Harris County, Texas | 100 |
| Cook County, Illinois | 100 |
| Bexar County, Texas | 99.9 |
| Collin County, Texas | 99.9 |
| Tarrant County, Texas | 99.9 |
| Dallas County, Texas | 99.8 |
| Denton County, Texas | 99.8 |
| Shelby County, Tennessee | 99.8 |
| Hillsborough County, Florida | 99.7 |
| Oakland County, Michigan | 99.7 |
🏠States with the most top-5% counties
🔎About this data
FEMA's long-run tornado risk score, compared with other U.S. counties. Not a count of tornadoes per year.
Source: FEMA National Risk Index v1.20 (December 2025), county scores
Coverage: Nationwide (counties)
Single source: FEMA's recorded tornado events for Oklahoma, Kansas and Alabama compared with NOAA storm records (moderate agreement, as expected for a long-run model). FEMA's scores are modelled estimates, so this layer is labelled single source.
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💬Questions and answers
Which county has the highest tornado risk?
2 counties share the top score of 100 out of 100 on FEMA's National Risk Index: Harris County, Texas, Cook County, Illinois.
Which state has the most high-risk counties?
Texas has the most counties in the top 5% (26 of the 159 counties scoring 95 or more).
What does the score mean?
FEMA's National Risk Index scores each county from 0 to 100 compared with all other U.S. counties: a score of 95 means the county's expected long-run losses are higher than 95% of counties. It is a model of risk over many years, not a forecast.
Where does this data come from?
FEMA National Risk Index v1.20 (December 2025), county scores. Coverage: Nationwide (counties).
Is the map free to use?
Yes. Map the Block is free, with no ads or paywall. You may quote figures with credit to Map the Block (maptheblock.com); for bulk or commercial use there is a Data API.
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Numbers computed from the live map data on October 18, 2026. Free to quote with credit to “Map the Block (maptheblock.com)”; see reuse terms.