Heat index values will be between 100 and 105 degrees.
CHICAGO (WLS) -- Chicago officials and medical professionals are warning residents about the dangers of extreme heat, emphasizing the importance of monitoring vulnerable populations, and taking precautions as temperatures rise.
The National Weather Service has issued an Extreme Heat Warning for Cook County until 10 p.m. Wednesday.
The NWS also issued a Heat Advisory for Boone, McHenry, Lake (Ill.), DeKalb, Kane, DuPage, LaSalle, Kendall, Grundy, Kankakee, Will, Lake (Ind.), Porter, Newton, Jasper, and Benton counties until 10 p.m. Wednesday.
The combination of heat and humidity may make it feel around or above 100 for several days in a row.
ABC7 AccuWeather Meteorologist Tracy Butler said it will be hot even along the lakefront.
Monday's highs are forecast for the mid-90s, with heat index values between 100-105 degrees with dewpoints in the 70s, Butler said.
SEE ALSO | How to stay cool in Chicago area amid rising temperatures this summer: LIST
Staff at Stroger Hospital of Cook County are watching closely for signs of heat-related illness, particularly among young people and older adults. Dr. Trevor Lewis, chairman of emergency medicine at Stroger Hospital, said seniors face heightened risks.
"A lot of seniors are on a lot of medications and some of those medications blunt the body's response of trying to get rid of excess heat, so they are just very vulnerable populations," Lewis said.
City officials reiterated warnings about the dangers of extreme heat and humidity, especially given the city's history.
Lewis recalled his experience as a hospital resident in 1995, when more than 700 people died during a devastating Chicago heat wave.
"It hit everybody. I'm not sure we were very prepared for it, and it was horrible what happened," he said.
City officials said that tragedy led to significant changes in how Chicago prepares for and responds to extreme heat. Former Mayor Richard M. Daley created the Office of Emergency Management and Communication in its aftermath to improve coordination among agencies and encourage residents to check on their neighbors.
Officials are urging people to call 311 for a well-being check if they are concerned about someone. Chicago Fire Department Commissioner Annette Nance-Holt stressed the importance of looking out for others.

"My heart is not to see that happen to any family member to find out you lost a loved one failed to check on them or failed to check if they had adequate conditions in their apartment or house," Nance-Holt said.
National Weather Service Meteorologist Mike Bardou warned that high overnight temperatures could worsen the effects of prolonged heat.
"The heat index value will probably only dip below the 90-degree mark for maybe six, seven hours a night, so recovery is minimal and that's what takes the toll," Bardou said.
Mayor Brandon Johnson also urged residents to stay safe and remain aware of the risks.
"Please keep cool this week and most of all, look out for one another. OEMC and the National Weather Service will work closely together to share alerts and resources to keep you informed," the mayor said.
The extreme heat has already affected emergency responders.
Chicago firefighters battled a house fire on West 73rd Street in Englewood earlier in the day. Although the house was vacant, officials said the physical demands were significant due to the high temperatures.

Nance-Holt said the department is taking additional measures to support crews in the field.
"We are sending additional ambulances out we are putting additional fire companies to help support troops in the field and we also have mandatory rehabilitation," she said.
Lewis encouraged residents to take simple precautions to reduce their risk.
"If you are going to be out in the warm weather, hydrate first try to stay ahead so drink maybe 12-16 ounces of fluid before you go out, and maybe 6 ounces every 20-30 minutes," he said.
The best way to avoid heat-related illness and stay safe is to stay indoors and use fans and air conditioning to keep your home cool, limit your time outdoors, stay out of the sun, wear loose, light clothing and drink lots of water and fluids to remain hydrated.
The city set up cooling centers across Chicago.
People can also find relief at one of the city's public libraries, Chicago Park District fieldhouses, as well as pools and splash pads.
As temperatures climbed, many residents sought relief at Oak Park's Rehm Pool on Monday.
Pool-goer Jessie Ortiz said access to public pools is especially important during the heat.
"The good thing is that the pools are open. So, I'm really happy because we get to really freshen up since this is one of our hottest we've experienced here in Chicago," Ortiz said.
Pool officials said they have prepared for increased attendance.
"We have more lifeguards to cover the pool. We've actually just added our activity pool. It opened this year to kind of up our capacity level to get more people in the building," said Lyra Arvetis, assistant manager at Rehm Pool.
Other visitors described the relief that comes from spending time in the water.
"My feet are burning but it was a good day to come to the pool," said Kash Thompson.
"Finally getting the water is like a cool bath, like the sticky sweat is washing out and it's so good," said Margaret Schinaci.
Elsewhere in the city, residents gathered for a concert in Millennium Park as temperatures eased Monday evening.
"It has been kind of hot and humid, but we do have such weather in Lebanon so were enjoying it to the maximum," said visitor Resha Khodor.
It's important when the temperatures climb to these extreme levels to check on your relatives, neighbors, seniors and those who are more vulnerable. You can always request a wellbeing check by calling 311.
Chicago Public Schools said their summer programming will be held inside through Wednesday.