The National Weather Service issued a Flash Flood Warning for DeKalb, Kane, Kendall and Will counties that was in effect 3:45 a.m. Tuesday.
A Severe Thunderstorm Watch was is in effect for Boone, Cook, De Kalb, DuPage, Lake, Kane and McHenry counties on Monday night, but it has since expired.
The Metropolitan Water Reclamation District of Greater Chicago issued a warning on Monday about heavy rain expected in the Chicago area.
MWRD recommends reducing your use of water before, during and after the storm to help prevent flooding and protect water quality. You can reduce your water use by delaying showers and baths, flushing less frequently and waiting to run the dishwasher or washing machine.
This new weather threat is coming just days after the strong storms we saw over the weekend.
The National Weather Service confirmed Monday night that two tornadoes touched down Saturday. One touched down near Elburn and the touched down near Wheaton.
Severe storms with high winds, heavy rain could arrive overnight
A cluster of thunderstorms began developing in southwestern Wisconsin around 7 p.m. Monday, ABC7 meteorologist Cheryl Scott said. Those storms are diving slowly southeast toward northern Illinois, and building up strength as they do.
The National Weather Service said that while the environment the storms are moving into is generally considered less favorable for thunderstorms, along with sunset comes a "low level jet stream" that is expected to develop to the west, and which could drag better fuel for these storms eastward and create a more conducive environment for severe storms.
The NWS expects the storms to stay west of Rockford until about 9 p.m., but could potentially spread east after that.
Southern Wisconsin and far northern Illinois are under a Level 3 risk for severe storms Tuesday morning, with strong winds being the main issue. Torrential downpours during the morning rush hour are also possible.
The rest of the Chicago area is under a Level 2 risk.
Storms were initially expected to move into the area after midnight and before daybreak, and to last until mid- to late-morning, but this cell of thunderstorms could change that forecast.
Storms are likely to fire back up Tuesday evening, and there's another chance for strong winds and hail. There's a low tornado chance.
Over the weekend, a Downers Grove church had its steeple damaged, as storms moved through the area.
Strong storms down trees, damage homes in north and west suburbs
Thousands were without power, as well.
Some homes in southern Wisconsin sustained structural damage.