SACRAMENTO - Even though clouds can cool temperatures on a hot summer day, temperatures feel hotter when it's humid.
The body cools itself by sweating. On a hot, dry day, the body sweats. The sweat evaporates and cools the skin by drawing body heat. On a humid day, the air is saturated, therefore the sweat doesn't evaporate as quickly. We are left feeling hot and sticky.
The "heat index" is what the temperature feels like on the body when the relative humidity is combine with the air temperature.
In order to determine the heat index, you need to know the temperature and the relative humidity. As shown in the accompanying chart, if the temperature is 94 degrees and the relative humidity is 40 percent, it will feel three degrees warmer.
The opposite is also true if the temperature is warm but the relative humidity is low, The heat index will make temperatures feel cooler.
