especially if humidity is high. From Science.org...

At wet bulb temperatures above 35°C, researchers estimate that even fit people will overheat and potentially die within 6 hours. Although that temperature might seem low, it equates to almost 45°C at 50% humidity, and what it would feel like 71°C using the U.S. National Weather Service heat index.

40 degrees Celsius is 104 F, but going up 9 degrees to 49 brings it up to 120 F. Plus the humidity? I think soon we are going to start seeing massive death tolls from extreme heat events.

One of his books starts with a wet bulb event that was devastating to read. He has a lot of books... i've forgotten which one.

It opens with an aid worker in India (I think) trying to survive a devastating heat wave and ends with him crawling out of the tepid pond in the middle of the town the morning after to a city centre full of corpses.

Devastating, and all too plausible the way the world is going. I also forget the name of the book, but I’d like to read it.

“The only mild summer was last summer “