CHICAGO (CBS) -- As the center of the Arctic air mass drifted overhead Tuesday night, temperatures were dropping below zero in all areas, including the city.
The National Weather Service has issued a wind chill advisory that began Tuesday night.
The wind chill advisory is in effect for all of northern Illinois and most of northern Indiana through noon Wednesday.
Temperatures are expected to drop as low as -6° in the city and -15° in the far west suburbs, with wind chills down to between -20° and -35°.
Winds that cold can cause frostbite on exposed skin in as little as 30 minutes.
If you do need to go outside Tuesday night or early Wednesday, limit your exposure, and dress in layers to protect yourself from the extreme cold – including a coat, hat, and gloves.
Wednesday morning will feature a low in Chicago of -6°, which will be the coldest temperature in the city since February 7 of last year.
Wednesday afternoon will be mostly sunny with highs in the low teens and wind chills below zero for much of the day. Not as cold Wednesday night thanks to the return of a south wind. Lows will be in the teens and highs Thursday will be in the low 30s.
As the next system moves in, it meets this extremely cold and dry air mass. So it will weaken, and we don't expect much system snow. The wild card will be any lake-enhanced plumes that set up Thursday night into Friday.
The high for Thursday is 30, Friday 20.
for more features.