Thunderstorms hit the suburbs Thursday afternoon and evening, and the risk for more severe weather is expected to last into Saturday.
The National Weather Service said Thursday "several rounds of heavy rainfall" is possible through Saturday. It calls for as many as 2 to 3 inches of rainfall.
The weather service also expanded its flash flood watch through Saturday evening. The counties of Cook, Lake, McHenry, Kane and Will are included.
The weather service says the most likely period for severe thunderstorms is through Friday evening.
"A very moist atmosphere will allow these storms to drop heavy rain over short amounts of time in some instances," a weather service statement said Thursday. "With recent heavy rainfall saturating the soil in many areas, runoff will quickly occur, increasing the potential for flash flooding and causing additional rises on area rivers."