Rain and fog may make driving difficult in the suburbs Sunday evening.
The National Weather Service has issued a dense fog advisory for much of the Chicago and Northern Illinois region through 11 p.m. Sunday.
Warmer Sunday weather, combined with rain and cooling temperatures into the evening and Monday morning, created foggy conditions throughout the area.
According to the advisory, widespread visibility will be reduced to a quarter of a mile, with some areas experiencing near zero visibility.
"Dense fog will make traveling by car or air challenging through tonight," the advisory states. "Those who must travel should plan accordingly. Be prepared for rapidly changing visibilities."
The National Weather Service suggested that those who are driving go slowly, make sure headlights are turned on and leave plenty of stopping distance while driving.
According to the FAA website, flights arriving at O'Hare International Airport are experiencing about a one-hour delay because of the weather.
Rain is expected to continue through Sunday night with more than .75 inches of rain already measured by midafternoon Sunday, according to the National Weather Service.
The weather service also issued a flood advisory on Sunday for urban and small streams due to rain and melting snow.