Having been in August 3 times so far, here is what works well for us..
*Stay hydrated... sodas and alcohol will have the opposite effect, so drink plenty of good old fashioned water.
* Wear lightweight, light colored clothes to reflect the sun, instead of absorbing it.
* Wear a lightweight light colored brimmed hat to protect your scalp and face from the sun.
* Wear at least SPF 15 sunscreen and apply liberally every couple of hours
* As much as you might want to peel off those tshirts, they actually keep you cooler, because when you sweat they absorb the sweat that evaporates and that keeps you cooler. Besides they don't allow anyone in the parks without shirts, shoes or some sort of pants, skirt, shorts, etc.
* Make sure you wear breathable, comfortable shoes with cotton socks. Take a change of socks with you, and some bandaids or moleskin if you are prone to blisters. Powder stick deodorant on blister prone places on your feet will help to prevent that problem.
* Do the bulk of your touring during the early morning or late afternoon/evening. AK is gets especially hot after about 11 am, so we usually do that park in 2 mornings.. or go back late to see the parade
* Take breaks during the hot part of the day. This is when we schedule our sitdown meal in an airconditioned restaurant. Or go back to your room, swim or shower, and change clothes. Or just find a shady place and kick back for awhile.
* Invest in a mister fan... not only will it help cool you off, but it will entertain the kids.
* Don't feel shy about playing in those fountains with the kids.
* Don't fret about the rain... it does help to cool things off.
* Know your signs and symptoms of heat exhaustion... and if you feel them, go to the nearest first aide station. Any Castmember will be glad to take you there...