Chicagoans can cool down Sunday before a major warm-up this work week.
On Sunday, the Chicago area will likely have fog and some showers in the morning with an isolated storm possible, then a partly sunny afternoon.
Before the heat wave hits the area, Chicago should see a cooler afternoon with highs in the low 70s.
According to the latest forecast models, Monday will be partly sunny with some isolated showers. Highs to start the week will likely climb into the high 80s, near 90 degrees.
Those warm temperatures will increase more on Tuesday, as highs reach the 90s. As of this weekend, the heat index Tuesday could be in the low 100s.
Another hot and humid day is expected Wednesday with highs again in the 90s and a heat index in the low 100s. However, Chicagoans could see a little ease by Thursday.
Mostly sunny, Thursday will have highs in the upper 80s, forecast models show.