After reading thru these posts, what "summer" means to some of you, would be a cool fall day for us down south, lol. Good advice has been given here, I can't add much, but I have had lots of experience in cutting in the hot TX weather, meaning above 105F. I have cut at 116F, and that was not at a low humidity either.
Take frequent water breaks, drink small amounts more often. Cool water, not freezing water.
Rotate your saws to let them cool down.
Keep a wet towel handy.
Don't jump into a cold air conditioned truck cab, then back out into the heat.
Keep a fire extinguisher handy.
Work slowly.
If you get fatigued, which you will very quickly, STOP. Resume the next day or take a long break and recover.
Don't forget to eat something, heat makes you not hungry, fresh fruits, bananas, "cool" foods are better, than say a chili cheese dog, lol.
Other than that, watch out for all the snakes, ticks, wasps, poision ivy and the such, and have a good time. Cutting in the heat is tiresome, but beats the heck out of not cutting at all.