The National Weather Service on Sunday issued a flash flood warning for part of northeastern Illinois including Chicago's northern metro area, after heavy rains flooded viaducts, stranded cars, and sent water surging into basements.
Chicagoans shared photos and videos on social media of cars partially submerged beneath underpasses and plumes of water shooting up from sidewalks.
The Chicago Bears showed no signs of canceling a planned football game with the San Francisco 49ers at noon local time (1700 GMT), posting videos of the team warming up in pounding rain on a sodden field.
Even after the heaviest rain had ended by around 11 a.m. CT, the NWS warned that roads would remain flooded until the water had time to recede.
The city on Twitter urged residents to avoid driving through standing water on streets, viaducts and low-lying areas.
The Intergovernmental Panel on Climate Change, or the IPCC, predicts more extreme flooding for the Midwest.
Extreme rainfall events - "very local, very intense, and hard to predict" - have increased in recent years, according to Chicago's water management office.
Such rains can dump 2 inches (5 cm) per hour on a neighborhood, overwhelming local sewers, filling mains and pushing water into residents' basements via private drains. As a result, the city has begun installing water blockers on catch basins that prevent sewers from flooding but can worsen street floods.
