Heat Index Table
Heat Index Readings
The heat index, sometimes referred to as the apparent temperature, is a measure of how hot it feels when relative humidity is factored with the air temperature. As relative humidity increases, the air feels warmer than it actually is because the body is less able to cool itself via evaporation of sweat.
As the heat index rises, so do health risks. Physical activity and prolonged exposure to heat increase the risks of getting a heat-related illness (or heat disorder).
The following chart shows the health risks as temperature and relative humidity rise:
Source: National Weather Service, Heat: A Major Killer
The following table describes likely heat-related illnesses (or heat disorders) from exposure to different heat index measurements:
See a larger image of the table.