A Freezing Rain Advisory was issued beginning at midnight Friday for counties north and west of Chicago.
The advisory was set to expire at noon Friday, but was extended to 7 p.m. and could potentially move into Chicago during the morning and afternoon hours.
Icy conditions could affect the morning and afternoon commutes, officials with the National Weather Service said.
By 10 p.m. Thursday, there were already reports of icy road conditions near Rockford as the first of two weather systems headed toward Chicago.
Several trucks were salting streets in McHenry and Woodstock overnight and Friday morning on the area's ice-covered roads. The National Weather Service said a glaze of up to a tenth of an inch of ice was expected.
McHenry County Sheriff's and Lake County Sheriff's offices said no major accidents were reported as of early Friday morning but officials were responding to multiple reports of cars sliding off the roads.
"My driveway was the worst," said Woodstock resident Julie Doeer. "I think the key is to just take it slow."
The afternoon commute could still be affected by the freezing rain as temperatures will hover in the low-30s for much of the day.
Friday evening should be dry but another system will begin dropping rain on Chicago's south suburbs early Saturday morning. Models show dropping temperatures, and that system is expected to drop rain to the south and snow to the north of Chicago.
A winter storm advisory was also issued for Saturday evening and extends through Sunday afternoon.
Accumulating snow is possible through Sunday evening. One weather model predicts up to seven inches of snow in the northwest suburbs and between two and four inches are expected to fall in Chicago and areas south. Northwest Indiana may just get rain.