Wet-bulb conditions

Wet-bulb conditions are the point at which humidity and heat reach a point the evaporation of sweat no longer cools a human being thus leading to the death of otherwise healthy persons. Scientists at Lamont-Doherty Earth Observatory, surveying data from weather stations between 1979 and 2017, found 7,000 instances of these conditions, mostly in South Asia, the coastal Middle East, and southwest North America.[1]

Wet-bulb conditions occur when relative humidity is above 95% and temperatures are at least 88° Fahrenheit, or, a wet-bulb temperature of 35° Celsius.[1][2]