Most of Illinois, including Lake County, is under a heat advisory from 10 a.m. to 10 p.m. today, July 17.
The temperature is forecast to reach 101 degrees, with a heat index of 105, according to the National Weather Service.
"These very hot and humid conditions will increase the risk of heat-related illnesses," National Weather Service officials said in a statement. "Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors."
The National Weather Service added that "anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency — call 911."