We spent 15 days in Disney in August when Hurricane Katrina horrifically hit New Orleans. Day by day we weren't sure if it was going to hit us at first.
First regarding the heat....HOT HOT HOT

And I remember people telling me how hot it would be before the trip...but until you experience a park mid day in August heat...you truly don't know lol. Would I go again in August...if it came down to that being the only time going or staying home...absolutely! It's Disney! We had about 12 of us with us. Age ranging from a 9 month old to my dad who was in his 60's and let's say a bit overweight. My advice...prepare yourself. Here is what we experienced.
We stayed off property....Personally I believe it would have been easier staying on property with direct access to parks so it would be nothing to go back and forth to parks...spending a few hours, heading back for a dip in the pool and heading back out at night. We would have to pack us all up back in the car (REMIND YOU THE TRACK GETTING BACK TO YOUR CAR)....extremely hot car...head back to hotel....then track back everyone to the park. Way too much for August heat with little ones and elders. Remind you also we were always in one of the first rows of parking each day because we just dreaded getting everyone to and from the parking lot.
So...TIP #1 - If possible stay in the park.
Tip #2 - If you have an elder person with you...rent the
scooter. My poor dad didn't the first day....come day 2...he was in heaven on his scooter, water bottles, cold towel on his neck and his little water fan LOL...I know what an image but....he had the best seat in the house!
TIP #3....Don't bother with makeup...hair....etc. To save time...shower the night before (since you all will be stinking from a day in the park in the Aug heat LOL)....and just get up brush teeth...throw hair up, but the lightest weight (no black!) clothes on....lotion up....and you're ready in 10 minutes.
TIP #4...Freeze water bottles in your room...and bring them with you. Keep hydrated!!! And believe me it doesn't take too long for them to start to defrost.
TIP #5...if you have a little one...make sure your stroller has a good sun visor....I would even put a wet cold towel over that to keep it even darker in there for him. I also layed a small cool wet towel under or on him....to keep him cool. Believe me...within minutes any wetness from the towel was gone.
TIP #5 ... Some people think everyone should wear hats in the sun. It works for some...but not my kids. I was told by the nurse there (one day my daughter needed down time there...heat really got to her)....that you shouldn't wear a hat in that heat especially if you tend to sweat more than others. The hat holds in the heat on your head...making you even hotter.
TIP #6 . . . get to parks at opening...stay for a few hours....head back to resort....nap, swim, freshen up....then head back out at dinner time. Even though night time was still hot...it was so much better without the sun beating on you. Another option...sleep in...hang by pool...do the parks with Extra Hours at night...some an be open as late as 3 am! My older ones rather do it that way....hard when you have an age range though.
TIP #7. . . Expect to get tired faster. And don't push ones that are....the heat can slow one person down so much more than maybe another. I learned that with my daughter. After that time we needed to take her to the medical place there....we learned that take breaks way before that happens.
TIP #8 . . . hit the water rides if you can. Getting soaked on a water ride is the best thing on this day....just be careful with shoes. Don't want blisters on top of being hot.
TIP #9 . . . Invest in some water fans. Fill them and freeze the water in it if you can.....the colder the water...the better they feel. You can get them anywhere...cheaper at home.
TIP #10...Be prepared for mid day storms. I mean downpours. One of the days we were at Universal and about 100 of us got stuck under this outside tent thing. It was the most scariest thunder and storm we experienced. Ponchos didn't work for us....some they do. We felt it just made us so much hotter with that plastic on us....we prefer to just duck in an airconditioned place....cool off, rest...dry off if need be. If you do have a stroller....invest in one of those plastic rain covers for it. I got mine at Babies R'Us....and always put it on when you leave your stroller when you go in a show. It may look like there is no rain in sight....but after the time passes of waiting to get in the show, watching the show, and finding your stroller....A downpour could have happened and you never knew it til you see your stroller soaking wet! LOL
TIP #10 ....I needed to repeat this STAY HYDRATED....with water.
MOST IMPORTANTLY......Have a Wonderful Trip! Regardless of the heat....kid's will still be amazed by Cinderella's Castle (heat or no heat)....kid's will still want to ride TOT 4 times...(heat or no heat).
When people say to me YOU SPENT THAT MANY DAYS IN THE PARKS WITH THAT FLORIDA HEAT? I said we sure did.....and yes it was HOT HOT...but it was the most wonderful trip we had. The heat couldn't damper the fact that my kids were in total shock when we woke them that morning and surprised them with a trip to Disney....The heat couldn't take away their expressions when they first walked through those gates at MK...and walked down main street and saw the Castle! The heat couldn't take away when Mickey and friends helped with singing to my son on his birthday.
LOL I think you get the point.
Just prepare yourself and realize it's ok if something got misssed. I seen parents dragging kids through that heat....the kids crying...and the parents wanted to make a show or something...and the poor child was just utterly done with the heat and being tired.
Hope that helps a bit....