A Wind Chill Advisory was in effect for Cook, DeKalb, DuPage, Grundy, Kane, Kankakee, Kendall, LaSalle, Lake (Ill.), McHenry and Will counties until 10 a.m. Friday.
SCHOOL CLOSINGS: Chicago Area Complete List
The advisory was in effect with wind chills of between -10 and -20 degrees, which the National Weather Service says can cause frostbite on exposed skin in as little as 30 minutes.
The city recorded minus 2 degrees shortly before sunrise at O'Hare International Airport, according to the National Weather Service. That is the coldest Chicago has been on Valentine's Day in 77 years.
That's one degree cooler than the city experienced in 1943, and was also the coldest day so far this season.
But it's still well above the coldest recorded Valentine's Day on record in 1905, when the city saw temperatures of minus 11.
RELATED: Look back at Chicago's coldest day on record
The weather has led to a few schools in the area to be closed Friday. For a full list, click here.
The bitter cold comes after another round of snow, with some places getting as much as five inches of snow.
WATCH: Winter surfers ride Lake Michigan waves
Friday will be sunny and temperatures will warm up over the weekend.
(Source: Sun-Times Media Wire - Copyright Chicago Sun-Times 2020.)