A fast-moving storm system raced through multiple counties in the Chicago area, sparking wind gusts as high as 99 miles per hour at the Gary, Indiana, airport and leaving hundreds of thousands powerless.
National Weather Service meteorologist Scott Baker said tornado teams were on their way to far southern Cook County and northern Will County to check for damage, but nothing has been confirmed.
Late last month, several storms ravaged the area, leaving neighborhoods in the south suburbs picking up the pieces after seven tornadoes touched down — damaging homes, uprooting trees and adding to what has already been an active tornado season in Illinois.
Rainfall and damage totals are also not in yet, said Baker, who added the rainfall will probably range between 1 and 2 inches.
“So severe weather has moved out and the thunderstorm watch and tornado warnings are all gone by now,” Baker said at 12:45 p.m.
A lakeshore flood advisory, including for the southern half of Cook County, does remain in effect until 5 p.m.
Earlier, the NWS said a severe thunderstorm watch would remain in effect until about 2 p.m.
Severe Thunderstorm Warning continues for Chicago IL, Cicero IL and Orland Park IL until 11:15 AM CDT. This storm will contain wind gusts to 70 MPH! pic.twitter.com/QG0vUFJHQp
— NWS Chicago (@NWSChicago) August 11, 2026
Just after 11 a.m.., the Gary, Ind. airport wind gust of 99 miles per hour happened and there were also reports of 81 mile an hour winds in South Barrington and 70 miles per hour in Oak Lawn, Baker said.
The strongest squalls erupted through a “kind of a corridor,’’ south and southwest throughout Cook County, possibly touching a little bit of DuPage and Kendall, Kane counties.
About 357,000 ComEd customers were affected by the weather, said a ComEd spokesman.
As of about 1:45 p.m., about 80,000 customers have had their electricity restored, he said. “We’re still looking at about 277,000 out.”
The storms also wreaked havoc on air travel.
As of about 1 p.m., delays were averaging 90 minutes at O’Hare with a total of 259 cancellations, according to FlyChicago.com. At Midway conditions were less severe, with delays averaging about 40 minutes, and only a handful of cancellations.
Those going to O’Hare have been recommended to check with their airlines for any flight-specific updates, as conditions change throughout the day.
18 total counties in Illinois were affected, including Cook County, with areas extending across northern and central portions of the state. Also including Livingston County in central Illinois; Ford and Iroquois counties in east-central Illinois; and Boone, DeKalb, La Salle, Lee, Ogle and Winnebago counties in north-central Illinois.
According to the NWS, the storm also impacted northwest Indiana and Wisconsin, affecting many communities near the I-74 corridor.
The weather service earlier urged residents to remain aware as the inclement weather moves through the region.
Along with the high winds, some areas potentially receiving around a quarter-inch or more of rainfall. Frequent lightning is also expected through the storm, with heavy downpours and flooding in certain areas being possible.
For the rest of the day, the Chicago area should be cooler and a little more light rain might move through. “We should see a little break this afternoon and then another chance of showers later this afternoon,” Baker said.
It will remain muggy, though as temperatures hover around 70 degrees at both airports.
“If you go out you won’t say ‘Oh, this feels great,’” Baker joked.
Tuesday night should stay pretty mild and Wednesday the temperatures will climb back into the the low 80s.
“We’re in a real unsettled weather pattern now,” Baker said. “It’s just wet and humid and everybody’s like, ‘Ok, we’re done with this.'”