The “wet bulb” temperature is better than simple ambient temperature (i.e. “dry bulb” temperature) however, it’s only part of the story. It fails to take a number of factors into account, when it comes to judging the danger of "heat related illness.”
Everyone knows that a “cool breeze” cools you off ("wet bulb" doesn’t measure this.) Everybody knows that being in full sun feels different than being in the shade (wet bulb doesn’t take this into account either.)
https://en.wikipedia.org/wiki/Wet-bulb_globe_temperature
https://perryweather.com/resources/what-is-wbgt-and-how-do-you-calculate-it/
What Is WBGT? Wet Bulb Globe Temperature Explained
Published on June 20, 2025 | Written by David Martin
What is WBGT?
DEFINITION
Wet Bulb Globe Temperature (WBGT) is a composite heat stress index that measures how the human body experiences heat in direct sunlight. It accounts for air temperature, humidity, wind speed, cloud cover, and solar radiation — making it the most complete picture of outdoor heat stress available.
Unlike the heat index, which only considers temperature and humidity in the shade, WBGT reflects real-world outdoor conditions. It’s the index used by the U.S. Military, OSHA, NFHS, and other governing bodies because it more accurately predicts when heat becomes dangerous — even for healthy, fit people.
Think of WBGT as your body’s true heat load, not the number on a thermometer. On a sunny, humid, windless day, your WBGT could be 10–15°F higher than the air temperature alone would suggest.
What does WBGT measure?
WBGT combines readings from three thermometer types, each capturing a different driver of heat strain. Together, they represent every meaningful way your environment adds heat load to your body.
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WBGT really isn’t
new, only the increased emphasis on it is. The use of multiple measurements requires a more sophisticated (i.e. more expensive) instrument than the traditional “wet bulb.” However, prices have fallen remarkably in the past few years.
https://nfhs.org/stories/wet-bulb-globe-temperature-wbgt-why-should-your-school-be-using-it
Wet Bulb Globe Temperature (WBGT) – Why Should Your School Be Using It?
BY JASON CATES, ATC, LAT AND JENNIFER D. RHEELING, MS, ATC ON APRIL 13, 2023 | 2023, APRIL, HST, SPORTS MEDICINE STORY
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