The National Weather Service issued a dense fog advisory for the Chicago area Monday morning.
The advisory is in effect until 8 a.m. for Cook, Kane, Lee, DuPage, Kendall, Grundy and Will counties in Illinois, the weather service said.
Fog is thickest and most widespread along north of Interstate 88 but some south and western suburbs will see dense fog through at least sunrise, the weather service said.
The fog could reduce visibility to a under a quarter-mile or a couple hundred feet at times, creating hazardous driving conditions, according to the weather service. Motorists are cautioned to use their headlights, slow down and leave plenty of distance ahead of their vehicles.