Which US counties are most at risk of tornado damage?

You may be surprised to learn that counties with major cities and high-priced real estate are some of the most at risk for tornado damage.

Chicago, Houston, Plano (Dallas Metro), St. Louis and Kansas City are all in counties that rank as the most vulnerable to damage.


File: Tornado damage in the Houston Metro area from Jan. 2023. (Brian Kelly / FOX Weather)

Gutter Gnome analysts crunched the numbers, looking at several factors:

  • Incidence risk: They scored counties with the highest risk of tornadoes, according to FEMA and NOAA, on a scale from 1-100. All counties scored at least 69.9. The score was weighted to account for about 42% of the ranking.
  • Financial risk: They scored counties based on the expected annual loss from tornadoes, according to data from the Census Bureau. This includes how dense the city is with buildings and relative costs. This accounted for about 25% of the ranking. That ranged from $1.5 million to $358 million.
  • Exacerbating factors: Finally, they scored counties according to the average age of homes, percentage of mobile homes and strong state building codes according to the International Code Council and the Census.

The age of the homes, between 24.5-70 years, accounted for 17% of the rank. The share of mobile homes ranged from 0.06%-42% and accounted for 12% of the final rank. State adoption of international residential building codes, ranging on a scale from 0 (no adoption) to 18 (most adoption), also accounted for 12% of the score.

Top 5 most vulnerable

Cook County, Illinois, took the top spot in the overall ranking. The Chicago Metro area had a tornado risk score of 99.97 out of 100. The average age of homes was 59.7 years, and only 0.77% were mobile homes. Illinois is tied for the lowest state adoption of residential and building codes. The annual expected loss from tornadoes is $304 million.



File: Lightning bolt strike Chicago's Willis Tower on April 4, 2023. (Craig Shimala via Storyful / FOX Weather)

Harris County, Texas, took the second spot. The Houston Metro area scored 100 out of 100 for tornado risk. The expected annual loss came in at $354 million. The average age of homes is relatively young, at 39.2 years, with 2.6% of them mobile homes. Texas has a moderate adoption of building codes.



File: Damage is seen in the Houston area after a tornado that swept across the eastern side of the metro on Nov. 21, 1992. (Tim Marshall/Haag Engineering / FOX Weather)

Collin County, Texas, which is northeast of Dallas, comes in No. 3. The home of Plano has a 99.94 tornado risk score and a total expected annual loss of $358 million – the most expensive. About 1.7% of homes are mobile homes, and the average age of all homes is 27.58 years.


In the fourth spot is St. Louis, Missouri, with an average home age of 70 years – the oldest average home age on the list of over 900 counties. The state is tied for the least adoption of building codes. The county which includes St. Louis has a low share of mobile homes, 0.34% and a tornado risk of 98.6 out of 100.



File: A highway sign sits in a parking lot at Lambert-St. Louis International Airport April 23, 2011 in St. Louis, Missouri after a tornado tore through. (Dilip Vishwanat / Getty Images)

Rounding out the top five, Jackson County, Missouri, also has a small share of mobile homes, under 1% and the average age of homes is 53.87 years. The expected annual loss for the home of Kansas City is $54.5 million with a tornado risk score of 99.59 out of 100.



File: Salvaged items sit in front of a destroyed structure in the Carriage Hills subdivision of the Kansas City suburb of Gladstone which was the victim of a tornado on May 5, 2003. (Brendan Smialowski / Getty Images)

The US leads the world in the number of tornadoes

The U.S. averages about 1,333 tornadoes a year. Half of those usually form between April and June. The second tornado season comes in the fall. Canada comes in second with just hundreds.

Texas is by far America's most active state for tornadoes, averaging 151 twisters each year. In a distant second place is Kansas, with an annual average of 91 tornadoes. This is an area some call "Tornado Alley."

Seven of the top 10 counties with the highest total expected loss are in Texas. Gutter Gnome nicknamed the area the "Texas Triangle."

Missouri, Kansas and Illinois counties placed high on the list because the states have not yet instituted building codes that mandate things like stronger roofs, safe rooms and impact resistant windows, explained Gutter Gnome.


The nation's most vulnerable counties for tornado damage

Source: Roof Gnome 2024

  1. Cook County IL
  2. Harris County TX
  3. Collin County TX
  4. St. Louis City MO
  5. Jackson County MO
  6. Sedgwick County KS
  7. DuPage County IL
  8. Milwaukee County WI
  9. Lake County IL
  10. St. Louis County MO
  11. Wyandotte County KS
  12. Wayne County MI
  13. Oakland County MI
  14. Denver County CO
  15. Tarrant County TX
  16. Dallas County TX
  17. Will County IL
  18. Madison County IL
  19. Jefferson County KY
  20. Kane County IL
  21. Hamilton County OH
  22. Johnson County KS
  23. Bexar County TX
  24. Winnebago County IL
  25. Hennepin County MN
  26. Sangamon County IL
  27. Cuyahoga County OH
  28. Philadelphia County PA
  29. Shelby County TN
  30. Lake County IN
  31. Macomb County MI
  32. Ramsey County MN
  33. Shawnee County KS
  34. Peoria County IL
  35. Marion County IN
  36. Jefferson County AL
  37. Potter County TX
  38. Reno County KS
  39. Douglas County NE
  40. Denton County TX
  41. Genesee County MI
  42. Jefferson County CO
  43. El Paso County CO
  44. St. Clair County IL
  45. Oklahoma County OK
  46. Pulaski County AR
  47. McHenry County IL
  48. Jasper County MO
  49. Saline County KS
  50. Travis County TX
  51. Minnehaha County SD
  52. Pinellas County FL
  53. Clay County MO
  54. Nacogdoches County TX
  55. Arapahoe County CO
  56. Jefferson County MO
  57. Woodbury County IA
  58. Cowley County KS
  59. McLennan County TX
  60. Hillsborough County FL
  61. Kent County MI
  62. East Baton Rouge Parish LA
  63. Robeson County NC
  64. Greene County MO
  65. St. Charles County MO
  66. Champaign County IL
  67. Dane County WI
  68. Lubbock County TX
  69. Rock County WI
  70. Hamilton County TN
  71. Gregg County TX
  72. Tulsa County OK
  73. Lucas County OH
  74. Jefferson County TX
  75. Los Angeles County CA
  76. Johnson County TX
  77. Lancaster County NE
  78. Polk County IA
  79. Adams County CO
  80. Weld County CO
  81. Montgomery County TX
  82. Butler County OH
  83. Calhoun County AL
  84. Waukesha County WI
  85. Franklin County OH
  86. Buchanan County MO
  87. Ingham County MI
  88. Allen County IN
  89. Etowah County AL
  90. Baltimore City MD
  91. Pottawattamie County IA
  92. Morgan County AL
  93. Pasco County FL
  94. Miami-Dade County FL
  95. Hinds County MS
  96. Johnson County IA
  97. Bell County TX
  98. Racine County WI
  99. Hunt County TX
  100. Boulder County CO

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