WeatherWorks wrote:The heat index utilizes temperature and dewpoint (or relative humidity) to determine how hot the body perceives the environment. Because the body cools down through the evaporation of sweat, moist air will not allow evaporation as readily as dry air. So, in turn, the body will feel hotter on days with higher dewpoint values.
I see Memphis weather says 92° with 78° dewpoint, which is getting into what they consider the "danger" zone - danger of heatstroke etc. Minneapolis 75° with a 68° dewpoint. Tucson is 108°, but a super dry 36° dewpoint makes it, well - "it's a dry heat." If anything less danger of heat exhaustion than Memphis, though 16° hotter on the thermometer.