Desert dweller with summer desert camping experience, here's some advice:
-PICKLES. Pickles are holy sent from above grade snacks. They are cool and refreshing and the brine helps you stay hydrated. They're easy to store and carry. There are different kinds if you don't like basic dill pickles. These were the most valuable item to barter at Wasteland Weekend.
-watermelon with salt. It's delicious. It's hydrating. The salt helps with electrolytes. KEEP IN MIND you need more than salt but salt will help
-Don't do shit during the middle of the day if you can help it. The middle of the day is siesta time, be lazy, stay in the shade, swim, nap, stay hydrated. Don't exert energy if you can help it. Get up early and/or stay up late to do work during the cooler parts of the day. That's when you can exert your energy.
-There are a bunch of great tutorials on rigging makeshift air-conditioning. Most of them are pretty cheap and easy to do.
-SHADE. STAY. IN. THE. SHADE! Shade makes the difference between tolerable and cooked well done. In AZ, shade makes the difference between a usable backyard and a completely unusable one.
-Put ice on your neck, feet, wrists. You can use a wet towel (dunked in ice water from the cooler is great), a zip lock baggie wrapped in a towel, snap towel, etc. REI has these cool neck bandanas with an insulated ice compartment (I really want to get a couple). Swim or take a cool bath if you can.
-LOOK AT ME. LOOK. I'm saying this with love. No you cannot hike with 100+ Temps with only flip flops and beer. A lot of idiots have to be helicoptered to hospitals doing that shit. DONT.
-Dehydration can look a lot like someone's lost their marbles and having an episode. If someone looks disoriented and out of it, they may be dehydrated. This happened to my boss and he had to go to the hospital for an IV. And he fought it because he didn't think anything was wrong.
-Sunscreen. Idc if you have darker skin. Sunscreen. You can still get cancer with darker skin. There are sunscreens out there formulated to not leave white cast. SUNSCREEN.
-Coconut water my beloved. Coconut water can give you a solid hydration boost that water can't. If you suffer from dry mouth it'll help coat your mouth and bring relief. There's Coconut water with pineapple mixed in if you don't like the flavor.
-if you're somewhere dry like the desert expect nose bleeds. Your nose will get dry if you're not used to it. A little bit of Vaseline on the edges and just inside your nose will help