CHICAGO (WLS) — Extreme heat is blanketing the Chicago area starting Wednesday, with heat index readings expected to be over 100.

The National Weather Service has put a Heat Advisory into effect for the Chicago area, starting at 10 a.m. Wednesday and lasting until 10 p.m. Thursday.

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The high temperature for Wednesday was expected to be 95 degrees, with heat index values of 100 to 110 degrees.

“Many people are unaware of how thirsty they are, and by the time you feel thirsty, you are already dehydrated,” stated Dr. Oyinkansola Okubanjo from Advocate Health.

Dr. Okubanjo emphasized the importance of being aware of bodily signals as temperatures climb to hazardous levels. A significant concern is the risk of heat stroke.

“If you notice that that person is not making any sense, they are already in heat stroke because the biggest thing we see is what we call mental status changes, so they are mumbling, they are muttering,” Dr. Okubanjo said. “Sometimes they could even have seizures, that’s really bad. Stop and call 911.”

OEMC is working to keep people out and about safe in the heat with cooling centers across the city. Cooling centers open at 9 a.m. Wednesday and Thursday and close at 5 p.m. both days, except for the South Kedzie location, which is open until 8 p.m.

How to stay cool in Chicago area amid rising temperatures this summer: LIST

People can also find relief from the heat in city libraries, police stations and park district buildings.

The best way to avoid heat related illness is to limit your time outdoors, stay out of the sun, and drinks lots of water and fluids to remain hydrated. People should also check on relatives and neighbors, especially if they are elderly.

The draw to water on Wednesday was irresistible. Residents and tourists had a hard time keeping kids from getting wet at the Crown Fountain and its water play in between the glass blocks.

In Auburn Gresham, Saint Sabina Church was giving water away at Racine and 79th street.

Water was just what Bobby Taylor needed. He had just finished mowing his sister’s lawn and he was done having to be outside.

“AC, that’s it, AC,” Taylor said. “I’m going to get out my clothes and jump in the shower and it’s over for me.”

Brenda Hayes is recovering from surgery and said the heat makes it harder for her.

“It’s taking a big toll on me,” Hayes said. “I am so hot it makes me so sick, all I can do is stay in the house.”

Emergency Room Dr. Michael Anderson at Advocate Healthcare urges Chicagoans to especially watch out for older residents.

“Elderly folks won’t notice one of the presenting issues can be confusion, and that interferes with decision making when we start to notice our home getting hotter,” Dr. Anderson said.

Some people could not avoid the heat on Daley Plaza Wednesday. Working inside a food truck, the temperatures quickly rise when they are busy making food.

“We learned this is not something to be played with, it is serious business out here,” said Veronica Linares, working at the LaCalaca Food Truck. “The weather can play a lot of tricks on you, you can get dehydrated, you can faint.”

The owners of La Calaca Food Truck said the temperature inside can 140 degrees.

“We all really focus on staying positive, checking each other out, if some one needs to step in making sure everyone is okay, and if they are not then we step in for them to step out for a little bit, and we all have our water bottles and we are ready to rock n’ roll,” Linares said.

“Make sure I stock up on water,” said Daniella Williams, who was exercising on Lakefront Trail. “I’m usually am bad at that. So I’m like oh my gosh the other day I felt like I’m dying, but I just add electrolytes.”

Early Wednesday morning, runners and cyclists took to the lakefront trail to get in some exercise before conditions become unbearable.

“You definitely feel the heat and humidity already. I can feel it pooling up in my hat,” Patrick Burke-McCoy, exercising on the Lakefront Trail, said. “It’s definitely warmer this morning than in past mornings.”

Campers at the nearby Columbia Sailing School worked to keep cool on the water…as the sun beams down.

“We’re encouraging lots of hydration and sunscreen, frequent swim breaks before and after they go out on the water,” Mike McBrien with Columbia Sailing School said.

McBrien says they are limiting how much time these young sailors spend under the sun.

“Shorter sailing sessions, a little more swimming and then trying to keep the kids in the shade,” he said.

An AccuWeather Alert for the dangerous heat will continue on Thursday.

For those who can’t stay inside or their home is not sufficiently cooled, there areresources around Chicago to help.

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