The Tennessee heat index was reported at a whopping 104.4 degrees, a new record.
It was also the fourth-highest temperature in the United States on Wednesday.
The heat index is a way of calculating how much heat a city or town can handle with less than 10 percent of its residents exposed to the weather extremes.
According to the Tennessee Department of Health, the heat index has increased each year since 2011.
In 2013, the index was 104.9.
The temperature in Chattanooga hit 105.1 degrees, breaking the record for the city in 2011.
A heat wave will be expected to hit Chattanooga and surrounding areas, including Nashville, Chattanooga, and Shelby County, Tennessee, as well as Nashville, Knoxville, Chattanooga and Shelby Counties.
The Tennessean reports the heat wave is expected to last until Monday and will continue through Saturday.
It says Tennessee has seen a record number of heat-related deaths this summer, with more than 3,600.
According the National Weather Service, the number of deaths due to heat- related deaths in Tennessee rose to 4,764 from 3,719 in the same period of 2015.