Why is everyone baffled about how brits don't cope with the heat though?
1/ We are not acclimated to it, our bodies have to work much harder in temps we're not used to, to function, to stay warm or cool down.
2/ Heat isn't the only factor, hot weather in the UK is usually accompanied by high humidity - humidity is currently around 60% in my area, going outside from an air con area currently feels like someones dumped a heavy sopping wet duvet on you. It makes sweating ineffective at cooling you down, and humidity plus heat plus no air movement is incredibly energy sapping.
3/ Routinely hot places typically have air con in homes and work places - we do not. It is mainly businesses that have air con and even then, only bigger companies. This means there is NO respite, we're too hot 24 hours without a break, we can't sleep, on top of the fatigue that the unaccustomed heat and humidity causes.
4/ Our buildings, our homes, workplaces and schools are NOT built to keep out heat, they're built to keep IN warmth and often, to let in as much light as possible. This makes them very very bad at keeping out heat!
That is why we bitch and moan, that is why we panic and that is why we take off all our clothes!