It seems that it depends on what phone you get. If you get a lemon, you are scr***d and if you get a decent one, you should be fine.
I was afraid that this phone is plagued with this overheating problem and while it is one of the "hottest" I have ever had, mine is under control. I did not manage to overheat it with normal usage of camera/hd video, but surely enough I would be able to overheat it with AR mode or 4k video.
Anyway, If I lived in a climate like yours, I would definitely not buy this phone!