It rained for 4 days straight when we were there earlier this month. When it wasn't raining, it was drizzling. The pictures look miserable but we had a blast! We did indoor things-- there are plenty of shows and rides that have covered stand-by lines. Get a poncho and wear it with pride. Get an extra one for your stroller and use it even when it is sunny. We came back to get our stroller one day and it must have rained while we were inside for other rides because it was swamped. For the next week, we covered it every time we left it.
Have a blast!! By the way, My DH and in-laws missed lots of fun by trying to wait out the rain. The kids and I did some great things while they watched the rain from a cafe.