The mercury dropped below zero just before midnight Sunday and has stayed there ever since. Readings dropped to a record-breaking low of minus 16 this morning at O’Hare and have rebounded only to minus 12 during the day. Temperatures are expected to drop down into the middle and upper teens below zero overnight threatening to tie or break the -16 record low for January 7. Slow moderation will begin Tuesday morning with readings climbing to or above zero by about noon on Tuesday ending a 36 hour subzero run.
Strong west winds will keep wind chills in the dangerous minus 30 to minus 50 range overnight but those numbers should steadily improve Tuesday as temperatures rise and winds decrease. The wind chill warning is expected to end at noon Tuesday.