A deep freeze has rolled in to the Chicago area, and people should be prepared for negative temperatures and wind chills not felt in more than a year.
The National Weather Service has issued a wind chill advisory for most of Illinois from 6 p.m. this evening and runs through 9 a.m. Tuesday.
Cook, McHenry, Lake, Kane and DuPage counties are all under the wind chill advisory.
Wind chill values overnight could reach negative-25 degrees, meteorologists warn, and the air will be cold enough to cause exposed skin to frostbite in one half-hour.
Officials are urging residents in the affected areas to take steps to avoid be exposed to the elements for prolonged time. People are urged to bundle up with a hat and gloves if outdoor travel is unavoidable, and wear layers of clothing to stay warm.
