I spent a summer in Washington DC. That was hot.
I spent a few years in the tropics, Jakarta is hot and muggy all the time but rarely gets above the mid 30s. I think the hottest it has ever been in Jakarta was 38C. Bangkok gets hotter than Jakarta but they have a "cool" season around Christmas, and I remember some days only getting into the mid 20s.
Adelaide has got to be one of the worst places in the world if you don't like heat. It gets ridiculously hot, like daytime temperatures in the low to mid 40s for a week or 2 at a time. The one time I visited Broken Hill the temperatures were similar, turns out that mid summer is not the best time of year to visit.
I'm lucky to live in a warm temperate climate, in general it isn't nearly as hot here in summer as it is in places like Washington DC, or Adelaide. But the hottest temperature I've experienced was here in Sydney, it was around 47 in this part of Sydney back in early January this year. And pushing 49 in other suburbs.
