UPDATE: A severe thunderstorm watch was issued for parts of Lake and McHenry counties in Illinois until 4 p.m. Tuesday.
Tuesday's dangerously hot weather, with heat indices of up to 115 degrees, also comes with the chance for severe storms, the NBC 5 Storm Team said.
While much of Tuesday will remain dry, some isolated showers could develop in the afternoon, NBC 5 Meteorologist Alicia Roman said. A better chance for showers and storms could come Tuesday evening.
The first round of storms could develop around 3 p.m. or 4 p.m. Roman said, with showers and storms stretching from Waukegan to through Aurora. By 5 p.m., the rain could move into Chicago, Roman said.
The next chance for storms comes around 10 p.m., Roman said, as scattered storms could develop across Chicago's southern counties. Those storms would move into Northeast Indiana overnight, Roman said.
Any storms that do develop could turn strong-to-severe, Roman said, with the entire Chicago area under a "slight" risk of severe weather, which ranks as level two of five on the Storm Prediction Center's scale.
According to Roman, the biggest threats Tuesday's storm carried were damaging winds up to 60 miles-per-hour, large and damaging hail and heavy downpours.
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Tuesday will also see an air quality alert for the entire Chicago area, including Northwest Indiana, the NWS said.
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As of 5 a.m., the air quality measured at "moderate," according to AirNow.gov, though Roman warned that the air quality was expected to worsen as the day continued.
"Moderate now, but later today, we will be upgraded to 'unhealthy for some,' which is level two of five," Roman said.
Excessive heat warning for Illinois
According to the National Weather Service, an excessive heat warning will go into effect at 12 p.m. Tuesday for the entire Chicago area. It's set to expire at 10 p.m., the NWS said.
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The alert brings "dangerously hot conditions," the NWS warned, with heat index values for most parts between 110 and 115 degrees.
High temperatures Tuesday will be in the upper 90s or even 100 degrees, Roman said, adding that the record high of 97 degrees, set in 1973, could be broken.
Such high temperatures and heat indices can "significantly" increase the potential for heat related illnesses, particularly for those outdoors, the NWS said.
"We're going to sound like a broken record, but limit your time outside, stay hydrated and drink lots and lots of water," Roman said.
MORE: 4 easy and fast ways to cool your body down in extreme heat
According to the Chicago Office of Emergency Management and Communications, 250 cooling centers across the city will remain active through Tuesday. Chicago Public Schools, which started the 2024-25 school year Monday, announced all outdoor athletic games and matches would be canceled through Tuesday due to the heat.
At least one Chicago-area high school has announced an early dismissal Tuesday due to the heat.
Temperatures Wednesday were expected to drop into the 80s, Roman said, though humidity levels were expected to remain high.
"Still very muggy," Roman said. "With dew point temperatures in the 70s, we still may have a heat index."
