Heat Wave to Hit Illinois with Temperatures Reaching 110 Degrees
A sweltering heat wave will take over Illinois Wednesday, with high temperatures in the mid 90s and “feels like” temperatures as high as 110 degrees, the NBC 5 Storm Team said.
“Very high heat index levels, very hot and humid conditions,” NBC 5 Storm Team Meteorologist Alicia Roman said.
Such high humidity and temperatures could lead to a slew of heat-related illnesses, ranging from heat cramping to the most severe, heat stroke.
Heat Advisory in Effect
According to the National Weather Service, a heat advisory will go into effect at 10 a.m. for nearly all of Illinois and Indiana. It will also be in effect for parts of Wisconsin, including Kenosha County.
“Peak afternoon heat index values of 100 to 110 expected,” the NWS warned. “Hot temperatures and high humidity may cause heat illnesses. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun.”
While Wednesday started out with lower dew point temperatures in the 60s, those will rise as the day goes on, Roman said, starting as early as 9 a.m. By around 3 p.m., heat indices are expected to peak.
Chicago to be “Stifling” Even at Night
The NWS added that the city of Chicago in particular will be “stifling” even at night, with heat indices remaining in the 90s through the evening hours, and temperatures only falling below 90 degrees for a few hours.
Here are additional details on the upcoming heat wave. The main impact will be stifling humidity levels, including during the overnight period. Heat index values will only drop below 90F for a few hours in the city of Chicago Wednesday night! #ILwx #INwx pic.twitter.com/nDwhoTHRPH
— NWS Chicago (@NWSChicago) July 22, 2025
Heat Advisory to Remain in Effect Until Thursday
The heat advisory will remain in effect through 10 p.m. Thursday, where heat index levels could reach as high as 105 degrees.
The Chicago Office of Emergency Management and Communications warned that residents could expect “dangerously hot conditions,” until some relief comes Thursday night. The city has also activated more than 250 cooling centers at community centers, senior centers, park district buildings, libraries, city colleges, police stations and more.
“Residents should contact 3-1-1 for the nearest location and hours,” the city said. Experts also recommended wearing loose, light-colored clothing, and applying sunscreen with SPF 30 or higher every two hours for those spending time outside.
Past Heat Waves in Chicago
The heat wave comes 30 years after a deadly, weeklong heat wave in Chicago that saw temperatures as high as 106 degrees and heat indices up to 120. The heat wave, which began July 13, 1995, left more than 700 people dead from heat-related illnesses. Most of those who died were elderly, lived alone, or didn’t have access to air conditioning.
Relief Expected on Thursday
About 3 p.m. Thursday, showers, storms and heavy downpours were expected to begin moving in, Roman said, which will bring temperatures down.
“The front will cool us off, with temperatures Friday dropping from the mid 90s to 84 degrees,” Roman said.
An on-an-off stormy pattern was expected to continue through the weekend.
Heat-related illnesses: Biggest symptoms to watch for
Dr. Oyinkansola Okubanjo, an emergency medicine physician with Advocate Health Care warned that heat-related illnesses are a “spectrum,” with symptoms people may not expect.
“The least [severe] is heat cramping,” Okubanjo said. “Where you feel like cramping in your stomach muscles, shoulder muscles, leg muscles. Okubanjo said that is usually due to dehydration, or low electrolytes.
After that, there’s heat syncope.
“A fancy word for passing out, because its too hot” Okubanjo said. “If that happens, that is concerning. You need to call 911.”
Heat exhaustion is more severe, Okubanjo said.
“That’s when you’re super sweaty. You’re drenched in sweat, you can barely talk, and barely stop to catch your breath. You’re really tired or fatigued,” Okubanjo said. Other symptoms include pale, clammy skin and muscle cramps.
If you don’t feel better in an hour, Okubanjo said, “you’re going to need to call 911, because you’re likely going into heat stroke, which is the most dangerous.”
Heat stroke is when your body temperature rises to over 104 degrees Fahrenheit.
“You can’t regulate your temperature,” Okubanjo said. “That’s a really scary thing. They can get really sick really fast.”
In heat stroke, you stop sweating, which means your body has stopped trying to cool off, NBC 5 Storm Team Meteorologist Kevin Jeanes said. Other symptoms include a throbbing headache, and red, hot dry skin.
The biggest symptom Okubanjo said to watch for, is confusion.
“If they’re not acting like themselves, call 911,” Okubanjo said. “It’s better for us to determine if they’re in heat stroke then for you to try and decide.”
Conclusion
A heat wave is expected to hit Illinois on Wednesday, with temperatures reaching as high as 110 degrees. The heat advisory will remain in effect until Thursday, and residents are advised to take precautions to stay safe. The city of Chicago has activated cooling centers, and experts recommend wearing loose, light-colored clothing and applying sunscreen. It’s also important to watch for symptoms of heat-related illnesses, including heat cramping, heat syncope, heat exhaustion, and heat stroke.
Frequently Asked Questions
What is a heat wave?
A heat wave is a period of abnormally hot weather that can last for several days or even weeks. It’s characterized by high temperatures and high humidity, which can make the air feel even hotter.
What are the symptoms of heat-related illnesses?
The symptoms of heat-related illnesses include heat cramping, heat syncope, heat exhaustion, and heat stroke. Heat cramping is characterized by muscle cramps, while heat syncope is characterized by dizziness and fainting. Heat exhaustion is characterized by heavy sweating, pale skin, and fatigue, while heat stroke is characterized by a body temperature of over 104 degrees Fahrenheit, confusion, and seizures.
How can I stay safe during a heat wave?
To stay safe during a
