The breach is in wet-bulb temperature, not dry-bulb temperature. When you hear weather reports cover the temperature, then it's going to be the dry-bulb tempera

The breach is in wet-bulb temperature, not dry-bulb temperature. When you hear weather reports cover the temperature, then it's going to be the dry-bulb temperature--the actual temperature of the air. Wet-bulb temperature is the minimum temperature you can reach by evaporative cooling (i.e., sweating). When wet-bulb temperature gets too close to core body temperature, you are physically incapable of shedding heat if you are not in air-conditioning, and how close it needs to be depends on how good health you are in. But we actually have seen deaths in previous heat waves, which largely didn't even breach 30C wet-bulb. The 2003 European heat wave caused about 70,000 people to die, for example.