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Wet-Bulb Temperature Calculator
Find the wet-bulb temperature from heat and humidity.
Wet-bulb temperature
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Stull approximation.
| In Celsius | — |
|---|---|
| Risk | — |
| Temperature | — |
| Humidity | — |
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Enter your figures above to see the step-by-step working.
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How the Wet-Bulb Temperature Calculator Works
Wet-bulb temperature is the lowest temperature you can reach by evaporating water into the air — it’s what a thermometer wrapped in a wet cloth reads. It combines heat and humidity into the single best measure of heat danger, because sweat can’t cool you once the wet-bulb temperature approaches your skin temperature. This uses Stull’s formula from air temperature and relative humidity.
A wet-bulb temperature around 88–95°F (31–35°C) is considered the survivability limit for humans even at rest in shade — the body simply can’t shed heat fast enough.
wet-bulb (Stull) = a function of air temperature and relative humidity
Frequently Asked Questions
What is wet-bulb temperature?
The lowest temperature reachable by evaporative cooling — the true measure of heat stress, combining temperature and humidity.
What wet-bulb temperature is dangerous?
Above about 88°F it becomes high-risk; around 95°F (35°C) is the theoretical survivability limit even at rest.
Why is wet-bulb worse than air temperature?
High humidity stops sweat evaporating, so your body can’t cool down even if the air temperature seems bearable.
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