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.

2021 Tornadoes: From January 1 to July 25, 2021, there were 784 tornadoes in the United States, compared with 797 in the same period in 2020, according to the National Oceanic and Atmospheric Administration (NOAA). There were 12 deaths in 2021, seven in Alabama, three in North Carolina, and one each in Louisiana and Texas. From January 2020 to July 2020, there were 73 deaths.

2020 Tornadoes: In 2020 there were 1,075 tornadoes compared with 1,517 in 2019, which was the highest annual total since 2011, when there were 1,691 tornadoes, according to NOAA. In 2020, 76 people perished in tornadoes compared with 42 in 2019. On April 12 and 13, 30 people perished in tornadoes in Georgia, Mississippi, South Carolina and Tennessee. On March 2 and 3, 25 people were killed in tornadoes in central Tennessee, including the city of Nashville. Tornado deaths in 2020 were the highest since 2011, when 553 people were killed in 1,691 tornadoes.

Insured Losses

Convective storms are the most common and damaging natural catastrophes in the United States, according to the Insurance Information Institute’s May 2020 white paper, Severe convective storms. According to Aon, insured losses in the United States from these storms totaled at least $10 billion each year since 2008. While scientists cannot say that these storms are increasing, it is clear that the losses are increasing, as a result of population growth and economic development. In addition, the geography, frequency and intensity of these storms also may be changing. Aon reports that there were 14 separate billion-dollar economic, or total loss severe convective events in 2020. The most expensive included the August 10 Midwest derecho, or straight lines winds. Aon’s current estimate of insured losses for severe convective storms in 2020 is a record $36 billion. The previous record was $32 billion in 2011.

The United States experiences more tornadoes than any other country. 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 $8.5 billion in insured damages (in 2020 dollars). The second costliest was the tornado system from August 8 to 12, 2020 that included the August 10 Midwest Derecho that caused $8.3 billion in insured losses.. (See chart below.) The National Weather Service posts updated information on tornadoes.

Convective storms are the result of warm, moist air rising from the earth, and depending on atmospheric conditions, may develop into tornadoes, hail, thunderstorms with lightning, or straight-line winds. Convective storms are the most common and damaging natural catastrophes in the United States, according to the Triple-I’s May 2020 white paper, Severe convective storms. According to catastrophe modeling company RMS, insured losses in the United States from these storms average about $17 billion each year, nearly equal to the losses incurred by hurricanes. While scientists cannot say that these storms are increasing, it is clear that the losses are increasing, as a result of population growth and economic development. In addition, the geography, frequency and intensity of these storms also may be changing.

According to Aon, there were 14 separate billion-dollar economic, or total loss, severe convective events in 2020. The most expensive included the August 10 Midwest derecho (straight line winds).

Natural Catastrophe Losses In The United States By Peril, 2020

($ millions)

Event Number of
events (1)
Fatalities Economic losses (2) Insured losses (3)
Severe convective storm 51 106 $49,323 $35,000
Tropical cyclone 12 73 40,059 21,600
Wildfire, drought, heatwave 19 43 22,959 13,900
Flooding 4 8 5,292 2,200
Winter storm 4 6 1634.1 930
Earthquake 4 0 152 58
Total 94 ~250 $119,000 $74,000

(1) Natural disasters that cause at least $25 million in insured losses; or 10 deaths; or 50 people injured; or 2,000 filed claims or homes and structures damaged. Includes Puerto Rico and the U.S. Virgin Islands.
(2) Includes any direct physical damage or direct net loss business interruption costs.
(3) Includes losses sustained by private insurers and government-sponsored programs such as the National Flood Insurance Program. Subject to change as loss estimates are further developed. As of February 23, 2021.

~ =Approximately.

Source: Aon.

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Number Of Tornadoes And Related Deaths Per Month, 2020 (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.

View Archived Graphs

The following chart shows the top 10 catastrophes involving tornadoes. It counts severe convective storms that may include tornadoes and other perils such as straight-line winds (derechos) and hail. The August 10, 2020, Midwest Derecho, which is included in the chart as part of the August 8-12, 2020 outbreak, would rank as the fourth-costliest insured severe convective storm event on record for the U.S. if considered alone. It caused $7 billion in insured losses in Iowa, Illinois, Wisconsin and Indiana.

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

($ millions)

        Estimated insured loss
Rank Date Event Location Dollars when occurred In 2020 dollars (2)
1 Apr. 22-28, 2011 Late April 2011 Super Tornado Outbreak AL, AR, GA, IL, KY, LA, MO, MS, OH, OK, TN, TX, VA $7,300 $8,490
2 Aug. 8-12, 2020 Includes Aug. 10 Midwest Derecho IA, IL, IN, KS, MI, MN, MO, NE, OH, SD, WI, PA, DC, MD, VA, WV 8,250 8,250
3 May 21-27, 2011 Joplin, MO Tornado AR, GA, IA, IL, IN, KS, KY, MI, MN, MO, NC, NE, NY, OH, OK, PA, TN, TX, VA, WI 6,900 7,990
4 May 2-5, 2003   AL, AR, CO, GA, IA, IL, IN, KS, KY, MO, MS, NC, NE, OH, OK, SC, SD, TN 3,205 4,570
5 May 27-30, 2019   CO, TX, OK, KS, AR, MO, IA, IL, IN, OH, PA, WV, WY, NJ, NY 3,650 3,730
6 Apr. 10-15, 2016 San Antonio Hailstorm TX, LA, OK, AR, MS, KS, MO 3,200 3,500
7 Apr. 6-12, 2001 St. Louis Hailstorm AR, CO, IA, IL, IN, KS, MI, MN, MO, NE, OH, OK, PA, TX 2,200 3,250
8 May 18-23, 2014   CO, DE, IA, IL, IN, MT, NY, OH, PA,
SC, VA
2,950 3,240
9 Oct. 5-6, 2010 Phoenix Hailstorm AZ 2,700 3,230
10 Mar. 2-3, 2012   AL, GA, IN, KY, OH, TN 2,500 2,850

(1) Defined by Aon as severe convective storms including insured thunderstorm events and may include tornado, hail, damaging straight-line winds (derechos) and flash flood impacts from events. Includes events that occurred through 2020. Subject to change as loss estimates are further developed. As of February 23, 2021.
(2) Adjusted for inflation by Aon using the U.S. Consumer Price Index.

Source: Aon.

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  • The costliest U.S. catastrophe involving tornadoes occurred in April 2011, when a spate of twisters hit Tuscaloosa, Alabama, and other areas, causing $8.5 billion in insured losses in 2020 dollars.
  • The second costliest was the tornado system from August 8 to 12, 2020 that included the August 10 Midwest Derecho that caused $8.3 billion in insured losses.

Top 10 States, By Number Of Tornadoes, 2020 (1)

Rank State Number of tornadoes Fatalities
1 Mississippi 127 12
2 Texas 102 4
3 Alabama 78 5
4 Georgia 75 9
5 Illinois 71 0
6 Minnesota 69 1
7 Florida 65 0
8 South Carolina 57 8
9 Louisiana 55 5
10 North Carolina 54 2

(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, 2020 (1)

State Tornadoes Fatalities Rank (2) State Tornadoes Fatalities Rank (2)
Alabama 78 5 3 Montana 2 0 37
Alaska 0 0 (3) Nebraska 35 0 13
Arizona 4 0 34 Nevada 0 0 (3)
Arkansas 41 0 11 New Hampshire 0 0 (3)
California 7 0 28 New Jersey 9 0 31
Colorado 34 0 14 New Mexico 21 0 25
Connecticut 6 0 30 New York 10 0 27
Delaware 7 0 28 North Carolina 54 2 10
D.C. 0 0 (3) North Dakota 22 0 20
Florida 65 0 7 Ohio 19 0 24
Georgia 75 9 4 Oklahoma 31 2 15
Hawaii 0 0 (3) Oregon 3 0 35
Idaho 0 0 (3) Pennsylvania 6 0 30
Illinois 71 0 5 Rhode Island 0 0 (3)
Indiana 39 0 15 South Carolina 57 8 8
Iowa 28 0 16 South Dakota 21 1 22
Kansas 27 0 17 Tennessee 38 27 12
Kentucky 23 0 19 Texas 102 4 2
Louisiana 55 5 9 Utah 0 0 (3)
Maine 2 0 37 Vermont 0 0 (3)
Maryland 21 0 22 Virginia 15 0 26
Massachusetts 3 0 35 Washington 2 0 37
Michigan 2 0 37 West Virginia 0 0 (3)
Minnesota 69 1 6 Wisconsin 22 0 20
Mississippi 127 12 1 Wyoming 1 0 42
Missouri 27 0 17 United States (4) 1,243 76  

(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 2020.
(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, 2001-2020 (1)

Year Tornadoes Deaths Year Tornadoes Deaths
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 1,126 10
2009 1,156 21 2019 1,517 42
2010 1,282 45 2020 1,075 76

(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, 2019

 

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

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