CHICAGO — It's official: the first snowflakes of the season have been spotted.
The National Weather Service recorded a "very wet" rain-snow mixture at O'Hare and Midway airports Tuesday afternoon, according to meteorologist Charles Mott.
Some suburbs in the area "have reported snow," Mott said. "But as far as Chicago goes, those are the only places that we've seen."
Forecasters weren't expecting any accumulation Tuesday, but said flurries might be possible throughout southern Cook County until about 8 or 10 p.m.
Snow before Oct. 25 is unusual in Chicago, according to meteorologist Matt Friedlien. Historically, the city only sees snow between Oct. 20 and Oct. 25 about once every 40 years.
"It's pretty rare," Friedlien said. "For October, you're talking a rate, even outside the city, once every 20 to 25 years."
Mott said Chicago's earliest recorded snowfalls happened on Sept. 25 in 1942 and 1928 — but residents only saw a few flurries each time.
The earliest "measurable" snowfall — meaning snow that accumulated for at least one-tenth of an inch — happened just seven years ago on October 12, 2006.
Tuesday's flurries come courtesy of a cold-air system from Canada that's sweeping across the region. It's causing low temperatures and peppering parts of the Midwest with snow.
Temperatures were forecasted to dip to about 30 degrees Tuesday night, but Chicagoans can expect highs in the mid 40s for the rest of the week. Things will warm up a bit this weekend with highs in the low-to-mid 50s.