I've worked in mines in the desert in South Australia where temps semi regularly hit 46-47 degrees.

It's OK (ish) because the humidity is low. But you can drink a litre an hour all day (11+ hours) and not need to pee. All that water goes somewhere.

The underground workings are often more dangerous, with lower temperatures but higher humidity. Once wet bulb temps get above 34 degrees underground personnel need to retreat from the area and the only work that can be done there then is work to fix the ventilation.

There's heat stress meters that measure wet and dry bulb temperatures and airflow, and can basically compute cooling power in watts. Not enough cooling power -> everyone out.

It's dry as a bone here right now. (That's good)

Also means it's all a big tinderbox. (That's bad)

Isn't this called wet bulb or something and lethal?

Actually at 100% humidity the highest survivable temperature for a human is 35 C° wet bulb temperature.
But that is with everything else being perfect, being healthy, in the shade, and perfectly hydrated, and zero physical activity.
A more realistic maximum survivable wet bulb temperature is closer to 30 C°. But 35 C° is the absolute maximum, where above that everybody dies.

Yup. Wet-bulb conditions are no joke and can kill, making functioning A/C a life-saving technology if not an outright requirement for survival.

South Australia doesn't have humidity.

40c is 104F, it's not common but it happens where I live at least a few times a summer.

49c is 120F that wouldnt be fun

My state high happened near where I live in 1934. 118 degrees.

Personally I think the highest I've experienced is 112.

Min of 35 is absolutely fucked

Dangerously hot, those are "fall and the sidewalk can burn you" temperatures.

And people forget wildlife don't have AC.

We'll be living in a dead world soon.

That is exactly how I felt about Texas.

And I was shocked no one thought to build or market reasonable 3rd spaces.

I always imagined thats why there were so many drunk people out and about. Because the only habitable place outside of homes were bars if you didn't have a gym membership.

I worked in Saudi Arabia for several years. According to the law, people working outdoors can have a break when it gets over 50. Usually, that law was actually obeyed. Hottest I ever experienced was 52. You don't have to out in that for long in order for it to be lethal, even if, as in my case, I was running every day in the desert and somewhat acclimatized to it. I'd go at 6 AM because that's the only time it wasn't infernally hot. The Bedouins, who know a thing or two about surviving the local climate, would get under cover and minimize activity when it got that hot.

Now I live in southwestern England, where it seldom gets above 30. I'm fine with that.

I live in Italy, in the valley around our biggest river. It's humid as fuck. Summers used to reach 32-35°C. Nowadays 40-45°C is not uncommon. Our offices are usually air-conditioned, but production areas aren't.

In Texas the hottest day I remember was 46 and that was miserable.

at body heat is also bad for your body. There is no temperature difference so heat doesn't go into/out of your body.

Alcohol and coffee being among the drinks to avoid once we get to wet bulb territory.

I guess not as wet bulb 35 already kills humans

The highest wet-bulb temperature ever recorded was 36.3C according to wikipedia. So very likely not that.