The weather service said scattered afternoon and evening thunderstorms will also be possible across the area. A heat index number of 108 is a "feels like" figure that means it's harder for the body to stay cool. What is the 'heat index'? The National Weather Service says the heat index, also known as the apparent temperature, "is what the temperature feels like to the human body" when humidity is combined with the air temperature, or the "feels-like” temperature. "In other words, the human body feels warmer in humid conditions.
