IL Winters Are Getting Warmer, Analysis of 45 Years Of Data Shows

ILLINOIS— Winter temperatures in Illinois have warmed by more than a half-degree per decade since 1980, according to a new analysis looking at how climate change has contributed to warmer winters in most of the country.

The analysis of winter temperature data from 1980-2024 by Harry Stevens, a columnist for The Washington Post’s Climate Lab section, showed 86 percent of the continental U.S. has trended toward warmer winters over the past nearly 45 years. About 14 percent of the country is getting colder.

In Chicago, winter has warmed 0.55 degrees per decade since 1980, the analysis showed. Also in Illinois during the same period:

• Springfield warmed 0.75 degrees per decade
• Rockford warmed 0.72 degrees per decade
• Joliet warmed 0.76 degrees per decade
• Peoria warmed 0.70 degrees per decade
• Naperville warmed 0.64 degrees per decade

Stevens’ analysis revealed New England winters are warming the fastest, possibly because of warming Atlantic Ocean water. “And warming winters feed on themselves,” he wrote. “With less ice and snow reflecting sunlight back to space, the land absorbs more heat, driving temperatures higher.”

Randomness may be the simple reason some areas of the country appear to be cooling, Ken Kunkel, a senior scientist with the North Carolina Institute for Climate Studies, told Stevens.

“Spatial variability is a natural part of the climate system,” Kunkel told the columnist. “I would actually be more surprised if you had found that the trends were the same, or nearly the same, everywhere.”

“Still, over a 45-year period in which nearly the entire planet has warmed, why do we find any cooling trends at all?” Stevens wrote. “And why in the western United States but not in the east?”

Though it is “still up for debate,” one theory is that the Arctic has warmed, polar vortex atmospheric winds have grown more unstable during winter, “sometimes spilling south into the United States,” Stevens wrote.

“Whatever the cause, something is stopping western winters from warming like the rest of the country,” he wrote.

» Read the full report on The Washington Post