A Dense Fog Advisory has been issued for Winnebago, Boone, McHenry, Ogle, Lee, De Kalb, Kane, DuPage, La Salle, Kendall, Grundy, Northern Cook and Northern Will counties until 9 a.m. Monday.
It is possible the National Weather Service may add more counties to the dense fog advisory ahead of Monday morning, ABC7 Meteorologist Jaisol Martinez said.
The conditions could cause trouble on the roads for drivers, who should use caution in areas of low visibility.
The fog also caused delays and at Chicago's airports. As of 4:30 p.m. Sunday, 38 flights had been canceled at O'Hare Airport and 24 flights and been canceled at Midway Airport, according to city data. Average flight delays at both airports were about 15 minutes.
FULL FORECAST | Chicago weather: Possible AM showers Monday, sun and clouds
There will likely be light rain showers across the area from 2 a.m. to 4 a.m. Monday, Martinez said.