Winter 2008-09—the coldest in 8 years—is to turn brutally cold the remainder of the workweek once snow exits Wednesday. Temperatures drop below zero Wednesday night and may remain there through Friday morning, producing what could be a 39 consecutive-hour stretch of subzero temperatures over many parts of the area (this sentence as published has been corrected). Only in the Loop and near Lake Michigan may the mercury struggle to zero (or just above) for a brief period Thursday—though that’s not guaranteed.

A full calendar day hasn’t failed to officially record an above zero temperature in Chicago since Feb. 3, 1996, when the high was 5 degrees below zero and the low was minus 19.

The snow Wednesday—the 26th day with measurable snow this season—is the product of the latest Alberta Clipper. With the storm system’s center tracking to Chicago’s south, winds just above the surface may take on an easterly component, blowing off the lake for several hours Wednesday afternoon and producing lake snow in addition to the system’s 1-4 inch snowfall.

21st coldest winter of past 139 years

Chicago’s 22.4 average temperature since Dec. 1 is 7 degrees colder than the same period a year ago.