The heat wave of 40 degrees a few weeks ago was intense not just because it was 40 degrees but because the night time temperates did not drop by much.
Usually in [redacted] while we have some very hot days once the sun goes down temperatures drop to the low 20s or even high teens so we can open the windows and our homes cool by heat exchange and it isn't too uncomfortable (without AC).
However recently we have had nights where it is still 28 or 29 degrees at 2am meaning it is still hotter outside than inside (indoor temperatures in my home without AC on is usually 25-26 even when it is high 30s outside) so opening a window just lets in warmer air. Without some kind of air cooling you end up with a hotter ambient temperature in your home which is horrible night after night after night.
And of course warmer rivers make nuclear power plant cooling more difficult.
I am from the UK originally so follow what is happening back in my home country too and the heat there has been insane as well. Highest recorded temperatures, way above what anyone can consider "nice" in a country with homes designed to keep as much heat in as possible and almost nobody having AC.
It is changes like we see here that worry me a lot for the future my son will be living in when he is my age. Really sorry state the world is in these days :(