A sharp Arctic front is poised to deliver a double dose of hazards across northern Illinois, with freezing fog early Tuesday giving way to bitter cold and dangerous wind chills later this week.
The National Weather Service in Chicago reports patchy dense freezing fog lingering through 8 a.m. CST, especially across areas west and south of Chicago, including Aurora, Joliet, DeKalb, and Ottawa. Visibility may drop to a half-mile or less, while slick conditions develop on bridges, overpasses, and untreated roads. Drivers should slow down, use low beams, and allow extra time for the morning commute.
By midweek, attention shifts to a powerful Arctic front sweeping through Wednesday night. Temperatures will plummet from the 30s Wednesday afternoon into the single digits by Thursday morning, with wind chills between -15°F and -20°F possible both Wednesday night and Thursday night.
Light snow may accompany the frontal passage Wednesday afternoon and evening, though accumulations are expected to remain under one inch. Behind the front, skies will clear, but the bitter cold will grip the region through the end of the workweek. Even daytime highs Thursday may only reach the teens, and Friday morning could bring another subzero wind chill round.
Cold river temperatures may also lead to rapid ice formation and potential ice jams along regional waterways.
Residents are urged to bundle up, limit outdoor exposure, and check on vulnerable neighbors and pets. The combination of freezing fog, icy patches, and Arctic cold marks the first deep winter surge of December for Chicago and northern Illinois.
