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Monthly and Annual Numbers of Tornadoes - Graphs and Maps

Tornado Reports

Tornadoes can occur anyplace, but they are more likely in some locations than others. Check maps that show the average number of tornadoes in each of the United States over a year or by month, based on tornado observations from 1991-2010.

Check the average number of tornadoes for various periods from 1991 through 2010 »

View maps showing the annual average number of tornadoes in each state »

View Billion-Dollar Weather and Climate Disasters »

Where do these data come from?

Official counts of tornadoes come from NOAA's National Severe Storms Laboratory. Storm spotters have been trained to recognize tornado conditions and report what they see to the National Weather Service. Storm spotters can be emergency managers or even local people with a keen interest in severe weather who have taken formal storm spotter training in their community. Additionally, computer programs, called algorithms, analyze Doppler radar data and display it in ways that make it easier for forecasters to identify dangerous weather. A storm with a tornado observed by radar has certain distinguishing features and forecasters are trained to recognize them.

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