I'm in the middle of Europe and it's not bad, the summer is actually pretty nice for my bad back that screams whenever it's cold. At most we had 38 I think, which is manageable. Now it's been raining for 2 days, and the random pressure variations are less to my liking.
On the hotter days it's just important to bring water everywhere and keep in the shadows wherever possible. I imagine it gets difficult in areas where the temps are much higher.