Gusting winds drove wind chills to minus-20 and whipped up a lake-effect squall that left more than half a foot of snow across Chicago and up to a foot in some parts of southern Cook County and northwest Indiana.
Temperatures are not expected to climb into the 20s until Friday and wind chills will plunge below zero every night, according to the National Weather Service.
"We're going to have the cold air stick with us for a while," said National Weather Service meteorologist David Beachler. "We're trying to rebound a little bit Wednesday, into the teens, but that's not going to last very long.
"We're kind of stuck in this pattern,," he said. "It's conducive to days on end of temperatures below freezing. It looks like it's going to persist until at least the end of the month and possibly linger ... into the first week of February.
"We might have a couple days where we warm up but it looks like we snap back into these pockets of cold air again," Beachler said.
No major storms are in the immediate forecast.
Chicago, southern Cook County and northwest Indiana were hit with an intense band of lake-effect snow overnight driven by gusts of more than 30 mph. As of 6 a.m., 5.9 inches was recorded at O'Hare International Airport and an observer reported 7.2 inches of snow at Midway Airport. Another observer reported 6.9 inches in downtown Chicago, according to the weather service.
Other totals included: Rogers Park, 6.5 inches; Highland Park, 6.5; Skokie, 4.5; Mokena, 3.5; Oak Lawn, 3.5; Wicker Park, 3; Evanston, 3; Glen Ellyn, 3; Romeoville, 2; Wheaton, 1.