Folks here run in the heat of summer, but it’s not humid here at all, so most of them get away with it.
Newcomers take a while to adjust, though. The sun and wind can suck the moisture right out of your body without you even knowing it.
My husband said they had to shut down the Chicago Marathon yesterday, because it was too hot. The winners were already done, but lots of people weren’t allowed to finish. I hope they gave them their money back!