Heat Index vs. Wet bulb globe temperature
Tools like the Heat Index and Wet-Bulb Globe Temperature (WBGT) help estimate environmental heat stress, but they serve different purposes and offer varying levels of precision. Understanding how these tools work—and how to apply them—can help athletes, coaches, and teams make more informed decisions when training in hot conditions.
Wet-Bulb Globe Temperature (WBGT)
WBGT is a more comprehensive measure of heat stress, factoring in air temperature, humidity, wind speed, sun angle, and solar radiation. It uses specialized devices to combine these elements, offering a more detailed view of environmental conditions during outdoor activity.
Outdoors with sunlight, WBGT is calculated as:
WBGT = (0.7 × Twb) + (0.2 × Tg) + (0.1 × Tdb)
- Tdb (Dry-Bulb Temperature): The standard air temperature measured in the shade
- Twb (Wet-Bulb Temperature): Reflects cooling from evaporation, influenced by humidity and airflow
- Tg (Globe Temperature): Captures radiant heat from sunlight using a thermometer inside a black sphere
WBGT is commonly used by sports organizations to help guide practice and game decisions in hot conditions.
Heat Index
The Heat Index estimates how hot it feels based on a combination of air temperature and humidity. It is often used in public health forecasts but does not account for solar radiation, wind, or reflective surfaces like turf.e Heat Index assumes you are in the shade.
Limitations: It assumes shaded conditions and is less effective in high-sun, high-intensity environments like athletic fields.
Why WBGT Is Used in Sports
WBGT offers a more detailed snapshot of real-world heat exposure—particularly important for athletes training or competing outdoors. Organizations such as the NCAA and state high school athletic associations use WBGT-based guidelines to help shape safe activity practices in hot weather. By considering more environmental variables, WBGT supports more accurate, real-time decision-making during training and competition.
This information is for general educational purposes only and is not intended to diagnose, treat, or prevent any medical condition. HeatSense does not provide medical advice. Always consult with a qualified health professional for health-related concerns.