Wet Bulb Globe Temperature (WBGT) is a measurement of heat stress that takes into account air temperature, relative humidity, wind speed, and solar radiation. WBGT is a function of Wet Bulb Temperature, Air Temperature, and Black Globe Temperature. In the 1950s, the US Military started measuring WBGT to help determine heat stress on recruits during training. A flag system was then created to easily alert people of potential hazardous conditions. Today's categories differ per region, but in North Carolina, we will use the levels determine by the National Weather Service and the North Carolina High School Athletic Association. In 2018, the NC ECONet started installing black globe thermometers at its stations to more accurately calcuate WBGT.