Update 7PM CDT…
Showers and thunderstorms have been primarily confined to the area south of Interstate-80 and remaining storms are drifting south. Activity should be slowly diminishing.
East to northeast winds behind a cold-front enhanced lake breeze have cooled temperatures back into the 70s along and just inland of the Lake Michigan shoreline this afternoon. However farther inland heat and humidity along with building cumulus clouds/widely scattered showers and a few thunderstorms prevail late this afternoon into the evening hours.
Inland temperatures have warmed into the upper 80s and lower 90s and when dewpoints in the upper 60s/lower 70s are figured in, the heat index is running in the mid to upper 90s at many locations. Showers/thunderstorms moving southeast 10 to 20 mph will become a little more numerous late this afternoon with brief heavy downpours, lightning, gusty winds and small hail likely in some of the strongest storms.
The Chicago National Weather Service has outlined the area most susceptible to the heat/humidity and t-storms on the map below.