Some homes, streets and vehicles were damaged in the south suburbs.
Video from Friday night in Lynwood shows a downpour.
There was flooding in South Chicago Heights and Steger.
Witnesses said some drivers needed to be rescued.
"We've got some serious flooding on all the side streets, main streets even, lots of cars in yards and stuff. It's pretty, pretty bad, houses flooding, basements flooding," Steger resident Ethan Willett said.
"I've lived here 23 years, and I've seen floods, but not this bad, to where the fire department had to come and walk a pregnant woman out of her car. It's really deep. It came down really hard and fast," South Chicago Heights resident Karen said.
There was also saw some ponding on the Bishop Ford Freeway near South Cottage Grove Avenue in the city. It was causing traffic to slow, but cars were making it through.
A Dense Fog Advisory was in effect for the area until 10 a.m., but the fog has since cleared out, only to be followed by thunderstorms.
Scattered showers and thunderstorms blew through Friday evening.
Authorities say at least four people are dead and several others injured after suspected tornadoes swept through southwestern Michigan.
In Branch County, the sheriff said a suspected tornado in the Union Lake area left three people dead and at least 12 people injured, including three who were hospitalized.
In Cass County, local officials said one person died and several other were injured after a suspected tornado touched down near Edwardsburg late Friday afternoon.
The weather is impacting operations at Chicago Midway International Airport and Chicago O'Hare International Airport, the Federal Aviation Administration said.
At one point on Friday morning, there were ground stops for departures to both airports.
According to the city's FlyChicago.com, 600 flights had been canceled at O'Hare as of 9:30 p.m. Just 22 flights have been canceled at Midway.
There are delays of about an hour at both airports.
The later evening hours are expected to be mainly quiet and mild with temperatures in the 60s.
After midnight, scattered showers and thunderstorms will push in along a cold front. These storms could also potentially become severe, with high winds and large hail being the main concerns.
Lingering showers during the morning hours on Saturday will quickly end. And the rest of the day, it will be quiet with temperatures falling into the low 50s by late afternoon.
The Associated Press and ABC News contributed to this report.