WBGT

WBGT stands for wet bulb globe temperature. It blends temperature, humidity, sunlight and air movement into one number. NWS calls it a particularly effective indicator of heat stress for outdoor workers and athletes.

OSHA calls an on-site WBGT meter the most accurate way to measure how environmental heat affects body temperature. OSHA's Technical Manual says OSHA uses WBGT to decide if a heat hazard was present. Many crews still use the heat index because it needs only a forecast. WBGT needs a meter, but it counts sun and wind. Learn when to use each in our WBGT vs heat index guide. Both feed a work/rest schedule.