Tornado Alley, in the central U.S., traditionally sees the most tornado activity, but tornado trends are shifting east, putting states like Tennessee and Kentucky increasingly at risk.
That’s according to a report by home services company Home Gnome that identifies which U.S. counties are most at risk for tornado damage as the 2025 peak tornado season begins.
The study uses FEMA data to analyze over 900 counties with moderate to very high tornado risk based on six factors, including tornado frequency, expected annual losses, average home age, and whether local building codes account for tornado resilience.
The Midwest has 14 of the 20 counties in the top 20 most vulnerable due to a combination of widespread tornado risk and older housing stock, which increases damage costs.
The South has 47 of the top 100 counties, notably in Texas and Oklahoma. That’s due in part to high percentages of mobile and manufactured homes, which increase the region’s vulnerability.
The report noted that old housing increases tornado vulnerability. Places at higher risk because of that include St. Louis City, Missouri (No. 2), and Philadelphia County, Pennsylvania (No. 90). Both counties could face high financial losses because of their dense populations and aging infrastructure. The Northeast is the least tornado-prone region in the ranking, and Philadelphia County is the only Northeast county the top 100.
The report’s authors noted that Kansas, Missouri and Illinois are tornado-prone but have not adopted standards from the International Residential Code or the International Building Code as statewide building standards. Some local jurisdictions use versions of the codes, which have been updated to include amendments focused on tornado resilience.
Most counties in the West have moderate tornado vulnerability, although Colorado has counties in the top 100, including Denver County (No. 11) and El Paso County (No. 20). At the opposite end, San Diego County ranks second to last (No. 945).
