What is Freezing Fog? Parts of Chicago Area Could See it This Week

With parts of the Chicago area under a Dense Fog Advisory Monday, some spots could see the threat of freezing fog.

The National Weather Service in Chicago issued the Dense Fog Advisory around 9 a.m. Monday for McHenry, Ogle, Lee, DeKalb, Kane, LaSalle, Kendall, Grundy, Winnebago and Boone counties.

It remains in effect until 1 p.m. with fog possibly reducing visibility to a quarter-mile or less.

As temperatures sat near or below-freezing throughout the morning hours, the advisory warns that the fog could freeze on roads creating slick conditions. Freezing fog occurs when temperatures dip below freezing and water droplets in the fog cool. The moisture then freezes on surfaces it comes into contact with.

Dense fog formed Monday as snow from Sunday’s system continued to melt and temperatures sat near freezing. 

There is also an elevated fog risk with limited ice accumulation possible by Tuesday morning, the National Weather Service said.  

Drivers are warned to slow down, use their headlights and leave plenty of distance ahead of them.

Contact Us