What is extreme heat?
Temperatures that hover 10 degrees or more above the average high temperature for the region and the last several weeks is defined as extreme heat. Humid or muggy conditions, which add to the discomfort of high temperatures, occur when a “ dome” of high atmospheric pressure traps hazy, damp air near the ground. Droughts occur when a long period passes without substantial rainfall. A heat wave combined with a drought is a very dangerous situation.