Chicago, IL – Temperatures will drop to 33°F by 1 a.m. Sunday, triggering widespread frost across northern Illinois and northwest Indiana that could damage plants and impact early morning travel routines.
According to the National Weather Service in Chicago, a Frost Advisory is in effect from midnight CDT (1 a.m. EDT) to 9 a.m. CDT (10 a.m. EDT) Sunday for areas including Rockford, Joliet, Naperville, Kankakee, and northwest Indiana communities like Gary and Valparaiso. A broader Freeze Watch follows late Sunday night through Monday morning, with lows expected to fall to 28°F in outlying areas and near 30°F across Cook County.
The coldest temperatures will occur just before sunrise Sunday, with frost forming on lawns, rooftops, and vehicles across suburbs from Elgin and Aurora to Downers Grove and Bourbonnais. Patchy ground fog may develop in rural areas, briefly reducing visibility. Major corridors including I-90, I-88, and I-55 should remain dry, but drivers should plan extra time to clear frost from windshields.
The more serious cold arrives Sunday night. Subfreezing temperatures could kill sensitive vegetation and damage exposed plumbing across Cook, DuPage, Will, and Lake counties. Residents should cover or bring in plants, disconnect hoses, and insulate outdoor pipes. Agricultural areas from DeKalb to Iroquois counties face increased crop risk.
Conditions improve after 10 a.m. Sunday, but another sharp drop begins after sunset. Additional alerts may be issued as confidence increases in the Monday morning freeze.
