Violent tornado outbreaks, like the storms that tore through parts of St. Louis and London, Kentucky, on May 16, have made 2025 seem like an especially active, deadly and destructive year for tornadoes.
The U.S. has had more reported tornadoes than normal – over 960 as of May 22, according to the National Weather Service’s preliminary count.
That’s well above the national average of around 660 tornadoes reported by that point over the past 15 years, and it’s similar to 2024 – the second-most active year over that same period.
I’m an atmospheric scientist who studies natural hazards. What stands out about 2025 so far isn’t just the number of tornadoes, but how Tornado Alley has encompassed just about everything east of the Rockies, and how tornado season is becoming all year.
The high tornado count in 2025 has a lot to do with the weather in March, which broke records with 299 reported tornadoes – far exceeding the average of 80 for that month over the past three decades.
March’s numbers were driven by two large tornado outbreaks: about 115 tornadoes swept across more than a dozen states March 14-16, stretching from Arkansas to Pennsylvania; and 145 tornadoes hit March 31 to April 1, primarily in a swath from Arkansas to Iowa and eastward. The 2025 numbers are preliminary pending final analyses.
While meteorologists don’t know for sure why March was so active, there were a couple of ingredients that favor tornadoes:
First, in March the climate was in a weak La Niña pattern, which is associated with a wavier and stormier jet stream and, often, with more U.S. tornadoes.
Second, the waters of the Gulf were much warmer than normal, which feeds moister air inland to fuel severe thunderstorms.
By April and May, however, those ingredients had faded. The weak La Niña ended and the Gulf waters were closer to normal.
April and May also produced tornado outbreaks, but the preliminary count over most of this period, since the March 31-April 1 outbreak, has actually been close to the average, though things could still change.
What has stood out in April and May is persistence: The jet stream has remained wavy, bringing with it the normal ebb and flow of stormy low-pressure weather systems mixed with sunny high-pressure systems. In May alone, tornadoes were reported in Colorado, Minnesota, Delaware, Florida and just about every state in between.
Years with fewer tornadoes often have calm periods of a couple of weeks or longer when a sunny high-pressure system is parked over the central U.S. However, the U.S. didn’t really get one of those calm periods in spring 2025.
The locations of these storms have also been notable: The 2025 tornadoes through May have been widespread but clustered near the lower and central Mississippi Valley, stretching from Illinois to Mississippi.
That’s well to the east of traditional Tornado Alley, typically seen as stretching from Texas through Nebraska, and farther east than normal. April through May is still peak season for the Mississippi Valley, though it is usually on the eastern edge of activity rather than at the epicenter. The normal seasonal cycle of tornadoes moves inland from near the Gulf Coast in winter to the upper Midwest and Great Plains by summer.
Over the past few decades, the U.S. has seen a broad shift in tornadoes in three ways: to the east, earlier in the year and clustered into larger outbreaks.
Winter tornadoes have become more frequent over the eastern U.S., from the southeast, dubbed Dixie Alley for its tornado activity in recent years, to the Midwest, particularly Kentucky, Illinois and Indiana.
Meanwhile, there has been a steady and stark decline in tornadoes in the “traditional” tornado season and region: spring and summer in general, especially across the Great Plains.
It may come as a surprise that the U.S. has actually seen a decrease in overall U.S. tornado activity over the past several decades, especially for intense tornadoes categorized as EF2 and above. There have been fewer days with a tornado. However, those tornado days have been producing more tornadoes. These trends may have stabilized over the past decade.
This eastward shift is likely making tornadoes deadlier.
Tornadoes in the Southeastern U.S. are more likely to strike overnight, when people are asleep and cannot quickly protect themselves, which makes these events dramatically more dangerous. The tornado that hit London, Kentucky, struck after 11 p.m. Many of the victims were over age 65.
The shift toward more winter tornadoes has also left people more vulnerable. Since they may not expect tornadoes at that time of year, they are likely to be less prepared. Tornado detection and forecasting is rapidly improving and has saved thousands of lives over the past 50-plus years, but forecasts can save lives only if people are able to receive them.
This shift in tornadoes to the east and earlier in the year is very similar to how scientists expect severe thunderstorms to change as the world warms. However, researchers don’t know whether the overall downward trend in tornadoes is driven by warming or will continue into the future. Field campaigns studying how tornadoes form may help us better answer this question.
For safety, it’s time to stop focusing on spring as tornado season and the Great Plains as Tornado Alley.
Tornado Alley is really all of the U.S. east of the Rockies and west of the Appalachians for most of the year. The farther south you live, the longer your tornado season lasts.
Forecasters say it every year for hurricanes, and we badly need to start saying it for tornadoes too: It only takes one to make it a bad season for you or your community. Just ask the residents of London, Kentucky; St. Louis; Plevna and Grinnell, Kansas; and McNairy County, Tennessee.
Listen to your local meteorologists so you will know when your region is facing a tornado risk. And if you hear sirens or are under a tornado warning, immediately go to your safe space. A tornado may already be on the ground, and you may have only seconds to protect yourself.
This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Daniel Chavas, Purdue University
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Daniel Chavas receives funding from the National Science Foundation, NASA, and NOAA. He is a member of the American Geophysical Union and American Meteorological Society. 
