Saturday was the fourth consecutive day of record heat in the Chicago area with temperatures hitting 95 degrees - the hottest this week.
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.
9 treated for heat-related issues in Waukegan
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.