Temperatures are expected to hit triple digits in the next few days, some might reach 107 degrees.
Doctors are warning people to take the heat seriously, because anyone who is outside is susceptible to heat related illness.
"You can go from just having some muscle aches to head aches to nausea, vomiting, stomach pain," says Dr. John Myers a physician at St. Mary's Convenient Care.
If you experience any of these symptoms, get out of the sun immediately and get hydrated, because if you don't the next stop might be heat stroke.
"That is a medical emergency. You get neurological changes, confusion, disorientation, seizures. You can't sweat anymore, you can have an a coma and die from that," says Dr. Myers.
For that reason the Red Cross opened more than a dozen cooling centers around the Tri-State.
"We just want folks to have a place to go where they can get out of the heat of the sun. If they don't have air conditioning at their house," says Matt Bertram, Executive Director at the American Red Cross of Southwestern Indiana.
Construction workers, farmers and anyone else who works outside have to be especially careful even if they are drinking plenty of water.
"We see construction workers who work hard for a day or two and on the third day they don't feel good. They think they drink enough, but they're behind so on the third day they have a mild form of heat exhaustion," says Dr. Myers.
For a full list of cooling center locations in the tri-state click here.