Severe Storm Potential Increasing In Illinois Due To Climate Changes: Study

A warming climate is increasing the potential for severe thunderstorms across Illinois, especially during the spring months, according to a new analysis of more than 20 years of government climate data.

Conditions that support severe thunderstorms have become more frequent in recent decades, according to a Climate Central report linking the uptick to changes in “convective available potential energy.” CAPE, as it is called, is a key measure of atmospheric instability that contributes to the development of thunderstorms with the potential to produce tornadoes, damaging winds and hail.

The most significant increases are occurring during the traditional severe weather season, from April through September, when the atmosphere is already volatile. As temperatures rise, warmer air holds more moisture, providing additional fuel for thunderstorms. That added energy can translate into stronger updrafts, heavier rainfall, and more damaging winds.

Climate Central’s analysis of National Oceanic and Atmospheric Administration data from 1979 to 2021 shows that springtime — already peak tornado and severe storm season — is seeing a notable uptick in high-CAPE days, signaling greater storm potential.

Midwest, Ohio Valley, South See Uptick

The increase in thunderstorm potential is strongest across parts of the Midwest, Ohio Valley and South.

Since 1979, some areas — including Kentucky, Tennessee and the central Ohio Valley — have experienced 10 to 15 more days each spring with high instability, a key ingredient for severe storms.

This aligns with broader research showing that the geography of severe weather risk is gradually shifting eastward, away from the traditional Great Plains “Tornado Alley” and toward more densely populated regions of the Midwest and Southeast.

Such storms accounted for nearly half of all billion-dollar weather disasters in the United States since 1980, according to data from NOAA’s National Center for Environmental Information.

Illinois had 92 severe billion-dollar storms from 1980 to 2024, cumulatively causing $20 billion to $50 billion in damages. The amount of billion-dollar disasters has increased over the decades.

In the 1980s (1980 to 1989), Illinois had three severe storm billion-dollar disasters, according to data from NOAA’s National Center for Environmental Information. But in just 2024 alone, Illinois had nine severe storm billion-dollar disasters.

Already this year, an EF-3 tornado struck south of the Chicago area, in Aroma Park and Kankakee County.

A More Volatile Future

Researchers caution that more favorable conditions for thunderstorms don’t always translate directly into more storms. Other atmospheric factors, such as wind shear, also play a role.

Still, the overall signal is clear: A warming climate is loading the dice toward stronger and more damaging storms.

“Warm, rising air is central to the formation of thunderstorms,” the report notes, and increases in atmospheric instability are expected to raise the risk of severe weather and related damage in the years ahead.

For communities across the United States, especially in the Midwest and Southeast, the findings suggest that severe weather preparedness may need to evolve alongside a changing climate.