Bundle up, Chicago, The first of two cold weather advisories this week was in effect for much of northeastern Illinois until 11 a.m. Monday morning, the National Weather Service said, with wind chill values or “feels like” temperatures as low as 20 to 25 degrees below zero.

Chicago and the surrounding areas remain under a cold weather advisory as dangerously below zero wind chills could cause frostbite within 30 minutes of exposure.

The cold Arctic blast lasts about 48 hours longer for the Chicago area, then a warming trend starts. Tuesday morning's temperatures remained cold, with overnight lows falling near zero. The brisk wind will send wind chill values towards -10° to -20° late Tuesday night and through early Wednesday.