Published on 15 Oct 2025
The widely accepted wet-bulb temperature survival threshold of 35°C is being questioned after recent physiological studies suggest the limit may actually be closer to 31°C.
Wet-bulb temperature is a measure that combines heat and humidity to show how well the human body can cool itself by sweating.
It's called wet-bulb temperature because it's measured using a thermometer wrapped in a wet cloth (or wick) over its bulb (the sensing part).
Normally, when we sweat, the moisture evaporates and cools our body.
But in hot and very humid conditions, this evaporation slows down.
If the wet-bulb temperature reaches the temperature of human skin (around 35°C), sweat can't evaporate at all — meaning the body can't cool itself, which can quickly lead to heat stroke or death.
In 2010, scientists suggested 35°C wet-bulb as the maximum survivable limit for humans.
But new research shows that people may start experiencing serious health risks at a lower level — around 31°C wet-bulb — especially if exposed for long periods.
Wet-Bulb Temperature
Temperature
Heat
Humidity
Health
Adaptation
Homeostasis
Thermometer