Exposure to excessive heat can cause illness, injury and death. The elderly, the very young, and people with chronic health problems are most at risk. However, even young and healthy individuals can succumb to heat if they participate in strenuous physical activities during hot weather.

A heat advisory is issued by the Arizona Department of Health Services when unusually high temperatures produce conditions that may lead to heat-related health hazards. The advisory is based on four factors – temperature, humidity, amount of cloudiness, and the expected duration of these conditions.