Another heat wave brings dangerous temps to Chicago area through Tuesday, forecasters say

Chicago is bracing for another stretch of extreme heat, with temperatures expected to soar and heat indices potentially reaching as high as 105 degrees, the National Weather Service said.

“Heat and humidity build in today through Tuesday,” the National Weather Service in Chicago posted Sunday on X. The heat index — a combo of heat and humidity— could reach the 100- to 110-degree range, especially on Monday.

“Conditions are possibly going to vary across the city, particularly on Tuesday,” said Lee Carlaw, lead meteorologist with the NWS Chicago office. “The peak heat-index values on Monday look like they will be in the 100 to 105 range in the city, coolest at the lakefront and then warmer as you work your way inland.”

There is the potential for some morning showers and thunderstorms, but forecasters say it's likely that rain will remain mainly west of the city.

“I cannot rule out the line of weakening storms moving into Chicago through the [Monday] morning hours,” Carlaw said. “If they do move through, it could have implications on the severity of the heat on Monday.”

If rain lingers into the afternoon, it could cut about 5 to 8 degrees or so off the heat-index values. As of Sunday night, the weather service said the most likely outcome will be heat indices in the 100 to 105 range.

Tuesday's forecast will be much the same, with heat-index values of 100 to 105. Another system of thunderstorms may move into the city Tuesday morning, bringing some relief.

“There's also a slightly greater chance of a lake breeze on Tuesday, which could spring a little more kind of immediate lakeshore cooling into areas close to the lake in the afternoon,” Carlaw said.

The NWS advises residents to remain indoors during the hottest parts of the day and to stay hydrated. Those most vulnerable to ill health effects from the heat include the elderly, young children and those without access to air conditioning.

“At this point, it seems like this heat wave will be possibly about the same as the one we just came out of recently,” Carlaw said. “We had a pretty significant heat episode in June that was probably a little bit more significant than this is looking to be, at least in the city itself. It seems like it will be hot, but the standard level of hot that we see in the city a couple times each year.”

To stay updated during severe weather events, residents can sign up for Notify Chicago, a free alert system from the Office of Emergency Management and Communications (OEMC) that sends updates via text or email. Subscribers receive notifications about extreme weather as well as other hazardous conditions and emergency information. To enroll, visit NotifyChicago.org.

A map of the city’s cooling center locations and additional safety resources are available here or by calling 311.