It's been a hot and humid summer across northern Illinois and southern Wisconsin, and we aren't done with the heat just yet. More steamy weather on tap for Thursday and Friday with highs in the upper 80's and heat index values approaching the low 90's. Southerly flow will bring more moisture into the area increasing dew points, and in turn increasing the humidity.
This will then set the chance for heavy rain producing storms on Saturday with a potent end of summer cold front that will dive southeast from the Northern Plains. This cold front will bring widespread showers and storms through Saturday afternoon. Not only that, but the front will also bring a big drop in temperatures from the upper 80's to the upper 70's by Saturday and then dropping again into the low 70's through Sunday! This is about ten degrees below average for August, which is 82°.
The cooler weather extends into a portion of next week with sunshine and highs in the mid 70's Monday and Tuesday before temperatures warm up a bit more. The Climate Prediction Center keying in on this trend through the end of the month through most of the country. The only areas with a probability to see above average temperatures will be both the west and east coasts looking to stay a bit warmer.