Facts + Statistics: Tornadoes and thunderstorms

Tornadoes

A tornado is a violently rotating column of air that extends from a thunderstorm and comes into contact with the ground, according to the National Oceanic and Atmospheric Administration (NOAA). In an average year about 1,000 tornadoes are reported nationwide, according to NOAA. Tornado intensity is measured by the enhanced Fujita (EF) scale. The scale rates tornadoes on a scale of 0 through 5, based on the amount and type of wind damage. It incorporates 28 different damage indicators, based on damage to a wide variety of structures ranging from trees to shopping malls.

The U.S. experiences more tornadoes than any other country in the world, according to a 2013 report by Lloyd’s of London. (See Executive Summary, page 4 of Tornadoes a Rising Risk? for additional findings and statistics.)

The Fujita Scale For Tornadoes

    Original F scale (1) Enhanced F scale (2)
Category Damage Wind speed (mph) 3-second gust (mph)
F-0 Light 40-72  65-85
F-1 Moderate 73-112 86-110
F-2 Considerable 113-157 111-135
F-3 Severe 158-207 136-165
F-4 Devastating 208-260 166-200
F-5 Incredible 261-318 Over 200

(1) Original scale: wind speeds represent fastest estimated speeds over one quarter of a mile.
(2) Enhanced scale: wind speeds represent maximum 3-second gusts.

Source: U.S. Department of Commerce, National Oceanic and Atmospheric Administration.

Tornadoes accounted for 40 percent of inflation-adjusted insured catastrophe losses from 1997 to 2016, according to Property Claim Services (PCS®), a Verisk Analytics® business. In 2018 insured losses from U.S. tornadoes and thunderstorms totaled $14.1 billion, down from $18 billion in 2017, according to Munich Re. The number of tornadoes fell to 1,124 in 2018 from 1,429 in 2017, according to the National Oceanic and Atmospheric Administration (NOAA). The 2017 total was the highest since 2011, when there were 1,691 tornadoes, including two spring events that resulted in more than $14 billion in losses when they occurred. There were 10 direct fatalities from tornadoes in 2018, compared with 35 in 2017, according to NOAA. May was the top month for tornadoes in 2018, with 155 twisters. The United States experiences more tornadoes than any other country, according to a 2013 report by Lloyd’s of London.

Preliminary NOAA reports show there were 1,431 tornadoes in 2019 through November compared to 1,060 for the same period in 2018. Tornadoes killed 38 people from January to November 2019, compared with nine people for the same period in 2018.

On March 3, 2019 a tornado struck southeast Alabama as part of a severe storm system that resulted in catastrophic damage in Alabama, Georgia, South Carolina and Florida. At least 23 people were killed in the March 3 tornado in Lee County, Alabama. In Beauregard, Alabama, the tornado left a half-mile wide path of destruction. The National Weather Service said that the tornado was F4 strength with top winds of 170 miles per hour. The tornado storm system of March 3 was the deadliest outbreak in the United States since a system in Arkansas and Mississippi in April 2014 killed 35 people.

There were 303 tornadoes in April which caused seven deaths: two each in Texas, Louisiana and Oklahoma and one in Mississippi. There were 556 tornadoes recorded in May. These tornadoes claimed another seven lives, including three in Missouri, two in Oklahoma and one each in Iowa and Ohio. Tornadoes from May 26 to May 29 in 13 states caused $2.8 billion in losses, according to the Property Claim Services unit of ISO. On October 20 and 21, a severe thunderstorm outbreak ripped through Texas, Oklahoma, Missouri, Arkansas, Tennessee and Louisiana, and produced several tornadoes including an EF-3 affecting the Dallas, Texas area. Aon said insured losses may reach the hundreds of million dollars.

Insured Losses

The United States experiences more tornadoes than any other country. Tornadoes accounted for 39.9 percent of insured catastrophe losses from 1997 to 2016, according to Verisk’s Property Claim Services (PCS). A March 2017 report by Willis Re found that the average annual loss from severe convective storms is $11.23 billion (in 2016 dollars) compared to $11.28 billion from hurricanes, based on PCS data. In 2018, insured losses from U.S. tornadoes/thunderstorms totaled $14.1 billion, up from $18.2 billion in 2017, according to Munich RE. The National Oceanic and Atmospheric Administration notes that tornadoes can happen any time of year. The costliest U.S. catastrophe involving tornadoes, based on insured losses, occurred in April 2011. It hit Tuscaloosa, Alabama, and other areas, and cost $8.2 billion in insured damages (in 2018 dollars). The second costliest catastrophe involving tornadoes, based on insured losses, struck Joplin, Missouri, and other locations in May 2011. The catastrophe cost $7.8 billion in insured losses in 2018 dollars. (See chart below.) The National Weather Service posts updated information on tornadoes.

Natural Catastrophe Losses In The United States, 2018

(Based on perils)

Source: © 2019 Munich Re, NatCatSERVICE; Property Claim Services (PCS®)*, a Verisk Analytics® business. As of March 2019.

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Number Of Tornadoes And Related Deaths Per Month, 2018 (1)

 

(1) Excludes Puerto Rico. A tornado that crosses state lines is counted as a single event in this chart.

Source: U.S. Department of Commerce, Storm Prediction Center, National Weather Service.

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Top 10 Costliest U.S. Catastrophes Involving Tornadoes (1)

($ millions)

      Estimated insured loss (2)
Rank Date Location Dollars when occurred In 2018 dollars (3)
1 Apr. 22-28, 2011 AL, AR, GA, IL, KY, LA, MO, MS, OH, OK, TN,
TX, VA
$7,300 $8,210
2 May 20-27, 2011 AR, GA, IA, IL, IN, KS, KY, MI, MN, MO, NC,
NE, NY, OH, OK, PA, TN, TX, VA, WI
6,900 7,760
3 May 2-11, 2003 AL, AR, CO, GA, IA, IL, IN, KS, KY, MO, MS,
NC, NE, OH, OK, SC, SD, TN
3,205 4,283
4 May 26-29, 2019 CO, IA, IL, IN, KS, MO, NE, NJ, NY, OH, OK,
PA, WY
2,835 2,835
5 Oct. 4-6, 2010 AZ 2,700 3,100
6 May 8-11, 2017 CO, MO, NM, OK, TX 2,507 3,041
7 Mar. 2-3, 2012 AL, GA, IN, KY, OH, TN 2,500 2,758
8 Apr 28-29, 2012 IL, IN, KY, MO, TX 2,500 2,758
9 Apr. 6-12, 2001 AR, CO, IA, IL, IN, KS, MI, MN, MO, NE,
OH, OK, PA, TX
2,200 2,563
10 Apr. 3-5, 2011 GA, IA, IL, KS, KY, MO, NC, SC, TN, WI 2,000 2,249

(1) Based on data through November 20, 2019.
(2) Property coverage only. In addition to losses due to tornadoes themselves, amounts may include losses due to hail, wind and flooding during the same event.
(3) Adjusted for inflation through 2018 by the Insurance Information Institute using the GDP implicit price deflator.

Source: The Property Claim Services® (PCS®) unit of ISO®, a Verisk Analytics® company; Bureau of Labor Statistics.

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Top 10 States, By Number Of Tornadoes, 2018 (1)

 

Rank State Number of tornadoes Fatalities
1 Louisiana 86 1
2 Iowa 84 0
3 Mississippi 68 0
4 Illinois 64 0
5 Alabama 52 0
6 Texas 52 0
7 Florida 48 0
8 Missouri 48 1
9 Kansas 45 0
10 Kentucky 41 1

(1) Tornadoes that cross state lines are counted in every state in which they touch down.

Source: U.S. Department of Commerce, Storm Prediction Center, National Weather Service.

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Tornadoes And Related Deaths By State, 2018 (1)

 

State Tornadoes Fatalities Rank (2) State Tornadoes Fatalities Rank (2)
Alabama 52 0 5 Montana 10 0 31
Alaska 0 0 (3) Nebraska 37 0 13
Arizona 6 0 35 Nevada 4 0 37
Arkansas 33 1 17 New Hampshire 3 0 38
California 6 0 35 New Jersey 0 0 (3)
Colorado 39 0 12 New Mexico 10 0 31
Connecticut 8 0 33 New York 11 1 29
Delaware 0 0 (3) North Carolina 41 0 10
D.C. 0 0 (3) North Dakota 31 1 18
Florida 48 0 7 Ohio 17 0 25
Georgia 21 0 22 Oklahoma 24 0 21
Hawaii 0 0 (3) Oregon 3 0 38
Idaho 11 0 29 Pennsylvania 31 0 18
Illinois 64 0 4 Rhode Island 1 0 43
Indiana 16 0 26 South Carolina 16 0 26
Iowa 84 0 2 South Dakota 19 0 24
Kansas 45 0 9 Tennessee 20 1 23
Kentucky 41 1 10 Texas 52 0 5
Louisiana 86 1 1 Utah 2 0 40
Maine 0 0 (3) Vermont 0 0 (3)
Maryland 2 2 40 Virginia 34 1 16
Massachusetts 7 0 34 Washington 2 0 40
Michigan 13 0 28 West Virginia 1 0 43
Minnesota 36 0 14 Wisconsin 35 0 15
Mississippi 68 0 3 Wyoming 31 0 18
Missouri 48 1 7 United States (4) 1,169 10  

(1) Ranked by total number of tornadoes.
(2) States with the same number of tornadoes receive the same ranking.
(3) State had no tornadoes in 2018.
(4) The U.S. total will not match data used in other charts because it counts tornadoes that cross state lines.

Source: U.S. Department of Commerce, Storm Prediction Center, National Weather Service.

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Tornadoes And Related Deaths In The United States, 1999-2018 (1)

 

Year Tornadoes Deaths Year Tornadoes Deaths
1999 1,345 94 2009 1,156 21
2000 1,071 40 2010 1,282 45
2001 1,216 40 2011 1,691 553
2002 941 55 2012 938 70
2003 1,376 54 2013 906 55
2004 1,819 36 2014 886 47
2005 1,264 38 2015 1,177 36
2006 1,103 67 2016 976 18
2007 1,098 81 2017 1,429 35
2008 1,692 126 2018 1,124 10

(1) Excludes Puerto Rico. A tornado that crosses state lines counts as one event.

Source: U.S. Department of Commerce, Storm Prediction Center, National Weather Service.

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U.S. Tornado Count, 2018

 

Source: U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service.

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Convective Storm Events* in the U.S., 1980-2018

(Overall and insured losses)

Source: © 2019 Munich Re, Geo Risks Research, NatCatSERVICE. As of March 2019. 

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Convective Storm Events* in the U.S., 1980-2018

(Overall losses: nominal, inflation adjusted, and normalized)

Source: © 2019 Munich Re, Geo Risks Research, NatCatSERVICE. As of March 2019. 

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