Beads of sweat will roll down faces around the Chicago area this week.
The heat index is predicted to climb to the mid-90s Tuesday and near 100-degrees by Wednesday.
The smoking hot forecast could be hotter though. The heat index could hit 110 Tuesday in parts of Downstate.
Forecasters issued an extreme heat advisory for central and southern Illinois. That includes more than 40 counties, but not Cook or the Collar counties.
The Health Care Council of Illinois urges people to limit their time outside. If they must go out, wear loose-fitting clothing, hats and sunglasses.