Chicago Weather

Excessive heat warning looms for Chicago area ahead of ‘dangerous' temps; 115 degree heat index

Prepare for temperatures to feel as hot as 115 degrees by Wednesday, the National Weather Service says

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Editor's Note: An excessive heat warning is now in effect for Northeastern Illinois. Our most recent story can be found here. Our original story continues below.

Although a heat advisory for much of the Chicago area Tuesday has been canceled, all of Northeastern Illinois on Wednesday will be under an excessive heat warning, with dangerously hot and humid temperatures that could feel as warm as 115 degrees, the National Weather Service said.

According to an alert from the NWS, at 11 a.m. Tuesday, a heat advisory for LaSalle County will still go into effect. Other counties, including DeKalb, Kane, Kendall, Kankakee and Grundy had previously been included in the heat advisory but have since been removed.

Temperatures Tuesday are expected to reach into the high 80s, but remain cooler and closer to the mid 80s along the lake. However, the air Tuesday in some parts could feel closer to 100 degrees "when you factor in humidity," NBC 5 Meteorologist Alicia Roman said.

And according to forecast models, the heat and humidity is only expected to keep building.

Wednesday: Heat expected to turn "dangerous"

What was earlier this week an excessive heat watch for all of Northeastern Illinois Wednesday has been upgraded to an excessive heat warning, the NWS said.

Temperatures Wednesday are expected to hit 98 degrees, potentially breaking a record of 97 degrees set in 1947, the NBC 5 Storm Team said. Additionally, "dangerously hot conditions with heat index values of 110 to 115 degrees are expected," the NWS said.

According to the NWS, Northwest Indiana currently remains under an excessive heat watch Wednesday, though that could change.

As heat builds, experts are advising residents to know the symptoms of heat-related illnesses, stay hydrated and remain in air conditioned spaces.

MORE: Suburban district delays start of new year, CPS promises A/C in all schools amid heat wave

Experts are also stressing the importance of not leaving pets or people in hot cars, as they can become deadly within minutes.

Hot cars can become deadly in a matter of minutes, experts say.

"Never leave children or pets in your vehicle," the Red Cross said. "The inside temperature of the car can quickly reach 120 degrees."

Additionally, the city of Chicago says it will open additional cooling centers this week.

Thursday: Excessive heat watch

Air temperatures will remain in the high 90s Thursday, and the area will be under an excessive heat watch, the NWS said.

According to the NWS, heat indices Thursday look to remain between 105 degrees and 110 degrees.

According to the NBC 5 Storm Team, some forecast models show thunderstorms could develop late Thursday into Friday, potentially disrupting the heat and keeping temperatures down.

Friday: Relief Arrives

The good news is the heat isn't expected to last long, as a cold front is expected to move in late Thursday night, bringing some relief by Friday.

High temperatures Friday are expected to sit in the 80s, dropping into the 70s by the weekend.

MORE: How is the ‘heat index' calculated, and how do weather officials use it?

The best advice for staying safe during Chicago's heat wave, according to experts

While advice from experts during periods of extreme heat may seem obvious, such heat "often results in the highest annual number of deaths among all weather-related disasters," a spokesperson for Cook County Health said.

So what exactly should residents keep in mind over the next few days as the mercury continues to rise? As NBC Chicago combed through dozens of lists and bits of advice from the Red Cross, the National Weather Service, the city of Chicago and more, these five tips were among the most cited.

Learn the signs (and differences) of heat-related illnesses

Heat stroke, heat exhaustion and heat cramps can all occur during periods of extreme heat, the Centers for Disease Control and Prevention says. However, all three may present different symptoms.

For example, those with heat stroke often exhibit red, hot and dry skin, with no sweat, the CDC says. Symptoms of heat exhaustion, the CDC says, includes heavy sweating. Here's a breakdown.

Stay hydrated

Drink plenty of water and fluids, the NWS said. "Your body needs water to keep cool," the NWS added. "Drink plenty of fluids even if you don't feel thirsty."

Additionally, drinks containing alcohol or caffeine should be avoided, the Red Cross said.

Keep your home cool and limit the use of your oven or stove

According to the Federal Emergency Management Agency, residents to "stay indoors as much as possible."

"If you don't have access to air conditioning at home, find places in your community with AC, such as a local cooling center," a release from FEMA said.

FEMA also recommended using curtains and awnings to keep the heat out to help keep homes cool.

According to the NWS, spending time in air conditioned buildings "markedly reduces danger from the heat. If you cannot afford an air conditioner, spending some time each day (during hot weather) in an air conditioned environment affords some protection."

"Keep electric lights off or turned down," Chicago's Office of Emergency Management and Communications said, "Minimize the use of your oven and stove."

According to the Office of Emergency Management and Communications, additional cooling centers will be open, and hours will be extended on Wednesday and Thursday, with residents able to get relief from the heat between 8:30 a.m. and 7 p.m.

Dress for summer

"Wear loose-fitting, lightweight, light-colored clothing," the Red Cross said. "Avoid dark colors because they absorb the sun's rays."

According to the NWS,  "lightweight, light-colored clothing reflects heat and sunlight, and helps your body maintain normal temperatures."

Don't leave people, pets inside parked cars

Hot cars can become deadly in a matter of minutes, experts say.

"Never leave children or pets in your vehicle," the Red Cross stressed. "The inside temperature of the car can quickly reach 120 degrees."

Pet owners should also frequently check on their animals to make sure they have plenty of cool water and shade, the Red Cross added.

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