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 2017 insured losses from U.S. tornadoes/thunderstorms totaled $18 billion, up from $14 billion in 2016, 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 that there were 492 tornadoes in 2019 through early May compared to 418 for the same period in 2018. Tornadoes killed 31 people so far in 2019, compared with 4 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 the 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.

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 2016 insured losses from U.S. tornadoes/thunderstorms totaled $14 billion, up from $9.6 billion in 2015. 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 $7.9 billion in insured damages (in 2017 dollars). The second costliest catastrophe involving tornadoes, based on insured losses, struck Joplin, Missouri, and other locations in May 2011. The catastrophe cost $7.6 billion in insured losses in 2017 dollars. (See chart below.) The National Weather Service posts updated information on tornadoes.

Natural Catastrophe Losses In The United States, 2018

(Based on perils)

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Natural Catastrophe Losses In The United States, 2018

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

num_of_torn_and_rel_deaths_per_month_18.gif

(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 2017 dollars (3)
1	Apr. 22-28, 2011	AL, AR, GA, IL, KY, LA, MO, MS, OH, OK, TN, TX, VA	$7,300	$7,880
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	7,591
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	4,191
4	Oct. 4-6, 2010	AZ	2,700	3,033
5	Apr 6-12, 2001	AR, CO, IA, IL, IN, KS, MI, MN, MO, NE, OH, OK, PA, TX	2,200	2,976
6	Mar 2-3, 2012	AL, GA, IN, KY, OH, TN	2,500	2,699
7	Apr 28-29, 2012	IL, IN, KY, MO, TX	2,500	2,699
8	May 8-11, 2017	CO, MO, NM, OK, TX	2,507	2,507
9	May 12-16, 2010	IL, MD, OK, PA, TX	2,000	2,246
10	Apr 3-5, 2011	GA, IA, IL, KS, KY, MO, NC, SC, TN, WI	2,000	2,200

(1) Based on data through June 6, 2018.
(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 2017 by the Insurance Information Institute using the GDP implicit price deflator.

Source: The Property Claim Services® (PCS®) unit of ISO®, a Verisk Analytics® company; U.S. Bureau of Economic Analysis.

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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