I was in the UK a few years back when it got into the 30s, and it was miserable. Windows didn't have screens and no one had fans. It seemed like the big change caught everyone off guard, and really roasted people. In Montreal, 35 degree days in summer were normal (-35 in winter) and the humidity was deadly, but we were ready for it for the 2 weeks it lasted. Talking to friends in interior Canada, it started early this year and hasn't let up a lot.
One of the reasons I wanted to live where I am now is that it stays cooler than that. It's sunny and 21c now. But the ocean temperature in the Bay has been up for 2 years running, and we're seeing dolphins and other creatures that rarely ranged up this way. They're welcome and very cool, but not a good sign.