According to the National Weather Service, light freezing rain is likely overnight Thursday into Friday and a glaze up to a tenth of an inch is possible.
"We thought, 'Oh, there probably wouldn't be too much ice out there,' but when you start walking it's really slick," said Val Karth, Woodstock resident.
In Woodstock, workers at a hardware store spread salt and sell it.
"Right when you think it's going to be slow, a couple more people come in. Yeah, definitely busier than usual," said Chelsey Aissen, Bohn's Ace Hardware Store.
In McHenry County, the trucks are loaded with salt and the crews are on the roads.
"We'll look at what the pavement temperatures are tonight, and based on that, when it is going to freeze, and then dispatch our crews based on that information," said Mark DeVries, maintenance superintendent, McHenry County Division of Transportation.
Everything here is ready in McHenry because the county is under a Freezing Rain Advisory that starts at midnight and lasts until noon on Friday.
"This seems like a very minor event with limited moisture to work with tonight, but it doesn't take much. It takes very little if it just starts to glaze up," said DeVries.
Lake County is also alerting residents via Twitter. "Watch for icy conditions," one tweet reads. "And use caution when walking, particularly on elevated or untreated surfaces."
They'll also be watching the roadways.
"We'll be monitoring the weather throughout the night and also contacting the weather service. If anything changes in the forecast is for freezing temperatures, rain or snow earlier, then we'll be deploying all 25 of our snow plow trucks," said Kevin Kerrigan, engineer of maintenance, Lake County, Illinois.
If the icing situation does develop overnight, it could impact the Friday morning commute.
"The first one is a smaller system, but could still produce some major problems because it doesn't take much ice to create very slippery roads, sidewalks," Caplan said.
Motorists and pedestrians should be aware that ice developing on area roads and walkways will result in slippery conditions.
Winter storm takes aim on busy travel weekend
The second storm system will hit during one of the busiest travel weekends of the year. The Chicago Department of Aviation expects more than 4 million passengers to travel through O'Hare and Midway beginning Friday and going through January 6. The busiest day at both airports is expected to be Friday.
"A winter storm watch is in effect for heavy snow Saturday night into Sunday evening," Caplan said, for Lake, Kane, McHenry and DeKalb counties in Illinois. "Significant snowfall is possible."
Aviation officials urge travelers to check ahead on the status of their flight and allow plenty of time to get to the airport and through security.
Meanwhile, south of the Kankakee River, Newton, Jasper and Stark counties are at a risk of heavy flooding from rain and snowfall over the weekend.