The National Weather Service has issued an advisory to report that freezing fog will create slick travel conditions late tonight.
According to the advisory, foggy conditions and temperatures in the lower to middle 20s have combined to produce a thin layer of ice and slippery spots on area roads.
Sidewalks and parking lots may also be icy.
The fog is expected to be dense from Bloomington through Champaign and on to Mattoon, making travel conditions hazardous.
Drivers are advised to slow down.
The low visibility from the fog is expected to improve at about 10 p.m. in central Illinois and shortly after midnight in extreme eastern Illinois.