I'm not a fan of tarps/covers/etc. It's pretty much impossible to get a good seal and the tarp might end up holding all the water in. That's what always happens to our boat that we leave outside all winter. If you want to keep it outside, just keep it where it won't get rained or snowed on. It'll be fine.

But if you're not going to ride it during the winter, just find a place for it inside. It might not make a difference, but I bet you'll feel better knowing it's always dry and safe.