Hazardous weather, including freezing rain and ice accumulation, is in the Chicago area forecast for Sunday.
Freezing rain, possibly mixed with sleet, is expected to begin Sunday morning and continue into the evening, according to the National Weather Service forecast office's website, crh.noaa.gov/lot.
Temperatures should warm up overnight, but before then there could be "significant" accumulation of ice on trees, power lines, pavement, sidewalks and other exposed surfaces, the site said.
Ice accumulation of up to 0.30 inches is possible, with the worst of it in northern Illinois in towns near the Wisconsin border.
Because the ground temperature is still below freezing, the icing threat could be prolonged, the website said.
Driving on untreated roads or walking on untreated sidewalks will be impossible without traction, according to meteorologists.
But if the temperature changes even one or two degrees, the type of precipitation may change, meteorologists said.
The weather service suggests having candles, flashlights and batteries ready for power outages.