The National Weather Service in Louisville has upgraded the area from a heat advisory to an extreme heat warning.
The warning remains in effect until 8 p.m. CT on Thursday.
The weather service advises area residents can expect dangerously hot conditions with peak heat index values between 100 and 115 degrees. Nighttime lows are still expected to be in the mid-70s.
The weather service advises people to make sure they are drinking plenty of fluids, limit outdoor activities and try to stay in air-conditioned areas as much as possible.
When necessary to be outdoors, wear lightweight and loose-fitting clothing and limit strenuous activities to early morning or evening hours.
Area residents are also advised to make sure they avoid leaving children or pets in hot cars, as it can only take minutes to reach lethal temperatures.
Vulnerable populations include those who are pregnant, newborns, children, elderly, and those with chronic illness.
