Most people are familiar with the heat index, but when it comes to outdoor sports, athletes and coaches may also be watching another important number: WBGT, or Wet Bulb Globe Temperature.
Unlike the heat index, which primarily considers temperature and humidity, WBGT also factors in direct sunlight, solar radiation, and wind.
That makes it a useful tool for estimating the amount of heat stress someone could experience while exercising outdoors.
Two days with the same air temperature can have very different WBGT readings depending on factors such as cloud cover, humidity, and wind.
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As WBGT climbs, athletic heat-safety precautions can increase. Schools may require:
- More frequent water and rest breaks
- Reduced equipment
- Shorter or modified practices
- Eventually, suspension of outdoor activities
WBGT is already incorporated into athletic heat-safety policies across the Carolinas.
In North Carolina, the NCHSAA provides WBGT-based heat guidelines for member schools. In South Carolina, the SCHSL requires WBGT monitoring during periods of high heat and humidity.
Locally, districts including Union County and Catawba County specifically include WBGT in their athletic heat policies.
During extreme heat, the temperature and heat index aren’t necessarily the only numbers schools are watching.
WBGT can provide a more complete picture of the conditions athletes are facing and help coaches and school officials decide when practices need to be modified or stopped altogether.