cybeardjm, From the vault: 2020
When the wet bulb temperature gets around 35°C, even a physically fit person resting in the shade with plenty of water would die within hours.
Potentially Fatal Combinations of Humidity and Heat Are Emerging Across the Globe
https://news.climate.columbia.edu/2020/05/08/fatal-heat-humidity-emerging/This is already happening - for brief periods - across the world.