A Heat Wave is a period of abnormally and uncomfortably hot and usually humid weather.
Heat waves can last from several days to several weeks.
East of the Rockies, they tend to combine both high temperature and high humidity although some of the worst have been catastrophically dry. Heat kills by taxing the human body beyond its abilities. In a normal year, about 175 Americans succumb to the demands of summer heat. In the 40-year period from 1936 through 1975, nearly 20,000 people were killed in the United States by the effects of heat and solar radiation. In the disastrous heat wave of 1980, more than 1,250 people died.