And accept you cannot control the weather. Especially in Aug- you are going rain or shine. They don't cancel and refund unless it's like tropical storm expected. (But if you chose not to go you can use the value of your non-refundable ticket toward another ticket in the future)
Just to clarify— it’s the value of a *
wholly unused* ticket that you can apply toward a future ticket.
You can’t have used any days at all. So if your first day you had good weather and enjoyed a day at a water park, but the rest of the days were awful and you decided not to go to any of the parks…. Then those days are wasted. And even if you are really flexible on travel dates, and can find lodging for additional days, you could still be screwed. Once you begin using the ticket, your “clock” starts on your countdown to the ticket’s expiry date… which is usually only a couple days longer than the number of days the ticket is for. (For example, a 3 day ticket expires 5 days after the first use, iirc.)
And another secret-that’s-not-a-secret

of note is that you can apply the ticket’s
full retail value, regardless of whether it was purchased thru Disney directly, or thru an authorized
discount reseller. If you used an authorized reseller, then obviously getting credit for the full retail price will work in your favor later if you are using an expired ticket toward a new one, or upgrading to one with more days, or putting it towards an annual pass (if available).
I just wanted to clarify that, because it’s a common misunderstanding that unused *
days* can be applied from a partly used ticket. That’s because a decade or so ago (maybe slightly more), there was a ticket type that had non-expiring
days and those tickets could be “prorated” (for lack of a better term) and exchanged for current ticket types…. But it is almost always a worse value to do that so it’s not recommended. (There’s other threads explaining why, so I’m not gonna get into that.)