The extreme heat sparked a medical emergency at a Junior ROTC event in Waukegan. Nine high school students were hospitalized for heat-related issues. No one was seriously hurt.
Meanwhile, Chicago area beaches were packed with people trying to keep cool - despite being one day into the official start of fall.
Sunday is expected to bring more heat with temperatures at 87 degrees by noon, hitting the lower 90s by the afternoon.
Organizers of the Chicago Half-Marathon & 5K, which will be held Sunday, are preparing for the heat with extra water, ice and misting stations.