[4:35 AM 8/21] Heat/Humidity builds this week. Here is a look at forecast peak heat indices; highest values expected Wednesday. Thunderstorm development over Lake Michigan remains possible which could disrupt heating across at least portions of the area. #ILwx #INwx pic.twitter.com/IiiEqQ99VO

— NWS Chicago (@NWSChicago) August 21, 2023