Much of Mississippi, Alabama, other parts of the South, as well as the Midwest, were under a heat advisory this weekend.
The National Weather Service said the combination of hot and muggy conditions produced heat indices from 105 to 115 degrees during the day. Overnight lows were projected to cool only to the mid 70s.
The weather service says the heat index is a measure of how hot it feels when the effects of humidity are combined with the temperature.
For example, a heat index of 105 degrees is considered the level where many people begin to experience extreme discomfort or physical stress.