The National Weather Service has issued an Extreme Heat Warning for the entire Chicago area, which will remain through Thursday.
ABC7 Accuweather Meteorologist Tracy Butler said highs are forecast to reach the upper 90s Wednesday, with heat index values between 102-107 degrees.
Butler said there is little relief from the heat during the overnight hours with high humidity.
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Storm chances begin late Thursday and there could be several rounds of heavy rainfall over the 4th of July holiday weekend, but Butler said it is not likely to be s washout.
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Doctors and city officials are reminding people to check on neighbors, stay hydrated and use cooling centers, if needed.
The best way to avoid heat-related illness and stay safe is to stay indoors and use fans and air conditioning to keep your home cool. Limit your time outdoors. Stay out of the sun. Wear loose, light clothing and drink lots of water and fluids to remain hydrated.
The city set up cooling centers across Chicago.
People can also find relief at one of the city's public libraries, Chicago Park District fieldhouses, as well as pools and splash pads.
Chicago Public Schools said their summer programming will be held inside through Wednesday.