my partner moved to the uk from an extremely hot country, and has said that the heat here is far worse due to the humidity and variation. vindicating.
Yeah, it's always the thing isn't it? It's not that it's hotter here than anywhere else, not that it's more humid than anywhere else. Hell no, we know it's worse elsewhere! It's a combination of factors that make it unbearable and I sorta wish that people got past the 'wow they're all weak' to understand how and why we react like we do. It's not a competition, I don't care to compete for 'who has it worse?' I'm just saying what it's like here and having people continually dismiss it as climate change gets worse is not fun.
Variation is a big one! Especially in temperature. It can jump 10 degrees in less than 24hrs, and our bodies cannot acclimatise that fast. As much as we may deal with 34c on holiday and manage it just fine, suddenly jumping from 18c to 29c does things to the body. It's why it takes a few days for people going on holiday to adjust to temp changes too. Then, of course, it just drops off. We'll slide from 38c straight back down to 20c in less than 24hrs, and it's difficult to adapt quickly to that too.
Humidity and the dew point are usually pretty high during these periods to. I mean it's always humid in the UK because this land is green due to being Wet™. So it'll have rained the entire week before, and then suddenly it shoots up 15 degrees and now you've got that humidity that pushes the feeling of the temps up higher. I know several people who've been to Florida, and several Floridians who've been to the UK who say it's roughly similar. It's a soup that feels difficult to breathe in.
No AC! We have AC in buildings (commercial) and on some public transport (newer trains, newer tube lines, newer buses, all cars etc), but it's not common in homes. It's becoming more common due to aforementioned climate change, but for many people it's expensive (£2000+ for basic) or difficult to install for various reasons (I'd have no issue because I own my house and it's not a listed building, but others in leaseholds/rented homes/historic buildings/have a shitty county council will struggle).
Our homes are well insulated (by regulation!) to keep out the cold and keep in the warmth. That means that the advice of 'throw open the windows and let the breeze in' is a terrible thing because that lets in the heat and it won't leave. It took over a week after the last heatwave for my house to finally cool to normal levels and that was with all the windows open. It holds it. Which is why the health service advice is to keep all windows and curtains shut that are facing the sun, and don't open them unless it's cooler outside than it is inside, or it's literally dark. Otherwise you're letting all the humidity and warmth in to stay.
Of course the issue with 'don't open your windows until the sun has gone down' is that the sun doesn't start setting here until after 9:30pm and isn't 'gone' enough to no longer cause the heat until after 10:30pm. So it stays hotter for longer! Tonight it will still be 31c at 9pm! It's not going to be cooler than inside my house (bedroom currently sitting at 26c because I have heat reflective covering on that window this time) until midnight. When will the sun rise? 4am and it starts getting hot again. Nighttime is no reprieve.
All of this really only occurs for less than 3 weeks of the year. Sometimes less than two because it's all so spread out.
It's not supposed to be this hot here! 10+ degrees above normal temperatures isn't a 'lmao weak' moment, that's a 'climate change is fucking real' moment and the answer isn't 'just install AC and live with it.' It should not be so hot in my country that the birds stop singing and the insects stop moving. We've got to start yelling at governments and dealing with those data centres because summer should be 'it was a little uncomfortable to sleep last night but it's okay' not 'I slept on my living room floor because if I slept in my bed I would die from the heat.'
So with all that, we exist with tower fans (which aren't effective over a certain temp and humidity) and hoping that this is over quickly.