as far as I know once you come thru the gate you've 'had your day' (which is why with afternoon thunder so common in the summer folks want their dolphin time EARLY)
HOWEVER there is a very liberal rebooking policy where if the weather is forecast to be a bust you can shift your date at no cost ...
"
Rebook without penalties or fees - shift reservations, up to 48 hours prior to your reservation date, to any future date through 2021*
Save Up to 30% on Rooms at Walt Disney World!
Save up to 30% on rooms at select Disney Resorts Collection hotels when you stay 5 consecutive nights or longer in late summer and early fall. Plus, enjoy other savings for shorter stays.This offer is valid for stays most nights from August 1 to October 11, 2025.
CLICK HERE