We just did WDW in July. Florida heat and humidity is no joke, but we had a great time. Going in heat is very manageable if you plan well. We definitely had hydroflasks with us like you will and I made sure to drink more than I even thought was necessary. Both TS and CS places will give you a cup of ice water when asked. I found the cup to be just about the right amount to fill my 26 oz hydroflask. Rope drop will also really work in your favor since morning will be cooler.
What we found worked:
- Taking breaks in the afternoon. It's the hottest part of the day, the lines are longest, and people are crankiest. We went back and took a nap and rested and then returned to the parks in the evening. If you don't want to go back to the hotel, find a nice air conditioned spot. The Animation Academy at DCA is the perfect spot for a break like that - we've used it
many times. It's fun to sit in there and watch all the scenes from different movies. I can't think of a spot at DL that stands out like that, but we've just ridden the train around the park to rest for awhile.
- Eating in table service or at least air conditioned spots. Don't underestimate the power of a good break in the AC to perk you right up.
- Bodyglide for feet. I have feet that tend to blister very easily, especially in hot and humid conditions. I used Bodyglide for feet every day we were in WDW and had zero issues. I wore socks and sneakers because of all the walking.
- Necklace fan! We used
this one and it was really helpful, especially in lines and when going in an out of AC. We didn't wear them all day, but they were useful when it was extra hot.
Some people like
cooling towels, but we didn't use them. WDW sells them on property; I'm not sure if DLR does. They're cheaper to purchase ahead of time, of course.
The good thing about Orange County is that even when it's hot, the mornings and evenings are still usually pretty pleasant.
Have a great trip!