I have the same worry too! and we're from Canada, so the humidity is an issue too!
We're going Aug 22-Sept 3rd.
I can't take the Kids out of school, and I can't do spring break or Christmas crowds - I have anxiety issues.
Our plan is Rope drop - noon, either a table service meal then back to the hotel, or straight back out to the hotel. We'll stay in till 4-6pm, depending on ADRs for dinner, then enjoy the parks till closing.
DS Chris age 16; DD Lizzy age 14; DD Ashleigh age 10 on February 12th!!!