Anytime you see a ride down it's highly likely it's due to weather if it's an outside ride. Or if it's inside it's just a mechanical issue.
It'll likely be up running soon, but could be down for a few hours.
If you're near the ride, ask the CM there if they know when it might be up and running. Usually they can tell you if it'll be up within the hour or they can tell you if it'll be down for 2+ hours