I live in the Desert Southwest, USA and we have already hit triple digits! Not knowing exactly which flush recipe/procedure you have chosen, I offer this advice: Most flushes have you cease intake of food and liquids a certain amount of time before you take the therapy. I would advise that you superhydrate, drink all the clean water you can, before that time. Than keep in the shade and try not to work up a sweat. Usually you can take a mouthful of water or so after the cut-off but keep it very minimal and no food or you could get very nauseous, I learned that the hard way.
I have done 3 cleanses and will also do another this weekend. I feel tremendous afterwards! I am coaching 2 other people on their fist cleanse this weekend also.