I've been to FL many times in August. I choose to visit in August because I enjoy WDW in summer.
I'll grant the current temps are above normal.
We do take some summer precautions though. In no particular order:
1. We get extra water with every meal, plus also carry a good amount of water. Maybe just us, but if we only relied on water at QS, we would not drink enough. If I have water in my hand, I drink water without thinking, so tend to do a better job staying hydrated.
2. We limit alcohol, caffeine, and beverages with artificial sweeteners. (By that I mean we don't sub coffee/beer for water.)
3. We do drink lemonade and juices: apple, orange, pineapple. In the last few years, we started getting (some) electrolyte water, and I've sparingly started trying the lemon/lime Liquid IV packets. Those are okay, but $$. Drinking some juice/lemonade seems to work better than all water.
4. We also eat lots of fresh produce in the summer. I don't know if it helps, but maybe it does. Once a week, we visit a local produce stand, then make a big pot of like vegetable stew. Whatever we buy goes in the pot: tomato, eggplant, pole beans, onion, summer squash, salt, a little water, balsamic, and maybe fresh basil. Very simple. It is so good! We eat it alone, or add noodles, beans, rice, good bread. (Plus fresh corn, and a big box of peaches/berries/etc.)
5. At WDW, we start early, break/nap (2-5pm), then come back out in the evening.
6. If anyone ever starts to feel like the weather is getting to them, respond quickly. (Get indoors, drink fluids, swim/get wet, sit for bit.)
7. Though not heat related: great footwear is always important at WDW. Summer footwear must be quality for walking, water tolerant, and have good treads. That usually = quality sandals. Bonus for adjustable straps.
