Most people understand that as the air temperature goes up, so does the heat index.
It's because the body's perspiration cannot evaporate as well when the humidity increases. Therefore, the cooling effects of your sweat are reduced as the humidity rises, and your body is unable to cool itself naturally. Several assumptions are used to calculate the heat index. Clothed in long trousers and a short-sleeved shirt. Walking at a speed of 3.1 mph.