You can buy sports towels that you wet in cold water and hang around your neck to keep cool. Of coarse they sell them at WDW but at 3 times the price as say Amazon
So I have been the past two years in the month of august. I would agree with most of what the above posters are saying…
Hit the park early AM, book a lunch, go back to swim, cool off in the ac and hit another park in the evening hours (if available at all)
Bring water and salty snacks to replace electrolytes.
Cooling towels are a must.
Be prepared for mid afternoon monsoons and possibly hurricanes (buy travel insurance)
Invest in cooling/breathable clothing/fabrics
bring a misting fan
bring stroller fans or fans for around your neck.
try to rotate a ride and a show so you get some AC time.
I’ve experienced pretty low crowds in august, so you can get alot done and have time for relaxation.
Be very careful with alcohol intake/dehydration can strike quick
Be prepared and you will have a blast!