Weather officials issued a dense fog advisory Thursday in effect until 9 a.m. warning of visibility less than a quarter mile creating hazardous driving conditions.
National Weather Service officials said the advisory covers portions of central, east central, north central and northeast Illinois, and Northwest Indiana.
Drivers should slow down, use headlights and allow space enough space between vehicles to safely stop.
A short period of dense fog was expected to hit the area Thursday morning, but conditions were expected to improve. Strong westerly winds were expected to develop later in the morning with gusts up to 35 mph into the afternoon, officials said.
The combination of ice on trees and power lines from previous days could result in power outages and tree damage in portions of northern Illinois.
Current conditions at Midway Airport included fog and mist with a temperature of 37 degrees.