Hi Connie,
You are right! July will be hot, but with the ability to cool off and rejuvenate, your Mouseketeers can continue on to enjoy more magic within the Parks. I answered the same question recently
HERE, where I discussed the many splash pads and tips to enjoy the cooling off time. Specifically at Disney's Animal Kingdom, you'll find misters near the Tamu Tamu Refreshments in Africa, or you could always pick up a Times Guide and plan to watch Finding Nemo - The Musical at the hottest part of the day. Another idea is to hop on the Wildlife Express Train and experience Rafiki's Planet Watch for awhile. At Disney's Hollywood Studios, besides the several indoor queues and attractions to avoid direct sun, head over to the Honey, I Shrunk the Kids Movie Set Adventure where you'll find a 52-foot water hose to cool down the little ones.
You'll also find the Baby Care Centers to be perfect respites or a place to change clothes, if needed, located in all four of the Walt Disney World Theme Parks.
Hopefully my suggestions are helpful, Connie, and I wish you a MAGICAL vacation.
Sherri