What rides will be closed at Disneyland in august?
Disneyland lists rides which are closed for planned
refurbishments on their daily schedule at their website (https://disneyland.disney.go.com/calendars/day/).
You can pick different days to see what rides are closed on that
day; it usually covers at least up through the end of the next
month. If you're planning your vacation in advance and want to know
what rides will be closed on a particular day six months from now,
you'd probably need to call and ask, though that far ahead the
schedule gets pretty iffy and they may not be able to tell you for
It's also possible that any ride may be closed at any time, even if it's not listed on the schedule, due to unforeseen circumstances.
The seasonal overlays go on and off pretty quickly (usually a couple of weeks or so); major repairs or refurbishments can take significantly longer. For example, the rides on Rivers of America have been/will be closed for a year or more, due to extensive construction in that area related to the new Star Wars Land.
Rides are only closed if the ride breaks down due to technical difficulties or if they're under-going "seasonal improvements." (Some rides have different displays/looks as the seasons change)