CHICAGO — The city recorded its warmest February this year.
The average daily temperature over the course of one of Chicago’s typically coldest months was 39.5 degrees this year, said Todd Kluber, a National Weather Service meteorologist. That’s a half-degree higher than the previous record set in 1882, Kluber said.
The city also had its fifth-warmest meteorological winter, with an average daily temperature of 34.9 degrees across December, January and February, Kluber said. The record of 37.2 degrees was set in 1877-’78.
Kluber said this winter was the warmest recorded by the weather service since moving its office farther from the lake, where temperatures are typically cooler, to O’Hare Airport.
Chicago has experienced a smorgasbord of seasons over the past week. Spring-like conditions are expected to return this weekend.
Max Grover, an atmospheric data scientist with the Argonne National Laboratory, said Chicago’s warming winter is the work of this season’s El Niño pattern — bringing a flood of warm air off the Pacific Ocean into the continental United States — combined with the impacts of climate change.
The balmy conditions have created “positive feedback,” a phenomena that accelerates steep climbs in temperature when winter is unseasonably warm, Grover said. With less snow and ice on the ground, the city has a harder time reflecting sunlight. Instead, water and dark-colored land absorb more sunlight and energy, a “nasty cycle” that traps heat in the atmosphere, Grover said.
Chicago is no longer experiencing the record-breaking winters and hallmark snow storms it saw throughout the ’70s, Grover said.
“Those multi-week stretches of sub-zero temperatures and a lot of extended extreme cold, we don’t seem to be having as often anymore,” Grover said. “Of all the seasons, winter is warming the fastest, especially in the overnight temperatures.”
While Chicago may see less major winter weather events, it doesn’t mean the city is out of the woods, Grover said. With the freezing line creeping farther north, Chicago could have fewer big snow storms and more sleet, “which I don’t think is much better,” Grover said.
“With less intense winter, we also have more exposure to pests, pollen and allergies,” Grover said. “Winter will still be bitter in ways, and there will be trade-offs.”
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