What Is the Heat Index? What To Know About the Metric During a Heat Wave

The heat index is a crucial metric that combines temperature and humidity to convey how hot it actually feels, rather than just the thermometer reading. This concept originated from a 1979 study, "The Assessment of Sultriness," which aimed to better understand the human perception of heat. During heat waves, the heat index becomes especially important as it helps people prepare for the potentially dangerous effects of excessive heat and humidity. Knowing the heat index can lead to better-informed decisions about outdoor activities and health precautions.