The National Weather Service said Lake and McHenry counties, along with the rest of the Chicago area, could see the first measurable snowfall of the season on Tuesday.
“Chances have increased for the first (minor) measurable snow amounts of the season for areas especially near and north of I-80 on Tuesday,” the NWS said in a statement.
Residents should expect precipitation developing Tuesday morning and a period of steady and brief heavy snow possible into the early afternoon.
The snow will change to rain from south to north by mid-afternoon on Tuesday, the NWS said.
Potential travel impacts include slippery roads due to snow and slush along with periods of poor visibility.
The NWS said Lake and McHenry counties have a 40-70% chance of measurable snow more than one inch.
Early Sunday morning, the NWS issued a Hazardous Weather Outlook for portions of North Central and Northeast Illinois and Northwest Indiana.
“Pockets of dense fog persist this morning and have been slowly expanding northward,” the alert said.
“If out traveling, prepare for visibility reductions as well as patchy slick spots where temperatures are still below freezing. Increase following distance and use low beams. Conditions should improve by this afternoon,” the alert added.