We have only experience a rain day once, it was a learning experience for sure. I think it was last year Oct.
We bought the Disney parks rain poncho's and the plastic smell was so bad, I could barely wear it. So I sucked it up, and used mine to cover our stroller. That was the most important thing to keep dry anyhow. They were expensive, I think it was something like $28 for 2 adults and 1 child.
So if you can, bring your own rain gear. Try to get one that your backpack or whatever can also fit under.
Our sneakers got drenched and the took forever to dry. That was the worst part. So bring alternative shoes if you can.
It was neat though, to see all the people in their Disney parks yellow rain coats. It was actually a cool sight, I'll have to go find some pictures and post. But, I always heard, the park gets pretty empty when it rains. But it never did, it was crowded. I don't think we went over to DCA, just stayed at DL, and honestly I can't remember a ride being closed down, but I could be wrong and not remembering correctly.
Have fun, just try not to let the rain damper your spirits and take it all in stride. Be prepared as best as you can, and roll with it. Even with rain, I'd rather be in
Disneyland then home anyday

haha