Big midweek warm-up before polar air returns

The 37-degree high temperature observed at O’Hare International Airport on Monday marked the first time in 17 days that readings climbed above freezing. Thawing temperatures were observed elsewhere, with highs at, or above 40 degrees from Waukegan, northward into southern Wisconsin. Cooler readings were observed south of the city where satellite imagery showed more extensive snow cover. Any remaining snow will melt over the next few days. Strengthening south to southwest winds are to lock in by Wednesday, sending temperatures into the 50s Wednesday night into Thursday. The spring like warmth will come to an abrupt end Thursday afternoon as a strong cold front passes. Temperatures by Thursday evening are expected to plummet into the 20s, with colder readings slated for the weekend.