We are one month away from our 3rd August trip and so far the info you are getting about August is excellent.
The extra shoes are NECESSARY
Water... water... more water... you can get free ice/ice water from any place that sells fountain drinks. My policy is if there is no line or a short line everyone get water every time you pass by a place (especially at AK becasue it's the hottest park don't ask why it just is). Staying hydrated is crucial to enjoying your vacation.
Walk through stores with A/C - if you have kids that beg for this or that, give them a daily budget and be firm. Or announce before you go into the store, we are going in for the A/C NOT for the merch.
If ANYONE in your group gets miserable - go inside and rest, whether its to eat, see Philharmagic, ride Soarin (yes it may have a long wait sometimes but hello it's got A/C) or go back to your hotel room. If it's someone who complains alot, they are only going to make everyone else angry because the heat makes for short fuses. If it's someone who doesn't complain alot, they may be verging on heat sickness. Either way, all you end up doing by not resting is making it miserable for everyone. Misery does not = fun.
Wear a hat and sunscreen. If you are prone to headaches, bring sunglasses and put them ON before you exit indoor attractions when it's bright outside.
Ladies bring a comfortable, lightweight (sports maybe) bra for EACH DAY, unless you plan to do laundry. There will be days when your bra will be soaked through with sweat. Do you want to wear it the next day?
I don't want to, I know that for sure. You could hand wash it and hang it in the bathroom too I suppose but hey I'm on vacation I don't do laundry.
OH and the most important thing is: Have FUN! We will be there Aug 16-20 and that's our biggest plan, having fun