For me it’s not about the actual temperature it’s about the dependability of the weather.
When I was a kid, cough-cough years ago, summer was weeks of decent weather. It might not have had the temperature extremes we’re seeing now but it was warm and sunny for weeks. Glorious, long weeks.
Now it feels like you can’t even plan a barbecue because it might be nice or it might be absolutely shitting down with rain.