WBGT = Web Bulb Globe Temperature
Wet Bulb Globe Temperature (WBGT) is a composite heat stress index designed to estimate how dangerous the environment is for humans—especially for outdoor work, sports, and military operations.
It goes beyond the heat index by including solar radiation and wind effects, not just temperature + humidity.
WBGT blends three components:
- Wet-bulb temperature (Tw) → humidity + evaporative cooling
- Black globe temperature (Tg) → solar radiation / radiant heat
- Dry-bulb temperature (T) → ambient air temperature
These thresholds are widely used (slight variations exist):
- < 80°F → Low risk
- 80–85°F → Moderate (fatigue possible)
- 85–88°F → High (heat illness possible)
- 88–90°F → Very high (danger)
- > 90°F → Extreme (training often suspended)
