Our MK day last month was a rainy day. And it rained hard!! We wore those disposable ponchos, but they were too big on the kids. Our jeans were soaked mid-way up to our calfs. It was also chilly, like in the low 60's or upper 50's. It was still alot better than the summer heat, but it didn't make it a super fun day. Our stroller got soaked and I wish I had a towel to dry it off (good suggestion from the pp). One good thing we did in the rain was go to Tom Sawyer Island. The paths are all paved so there's no mud. There are alot of tress to cover you, and then there's all those caves. We practically had the place to ourselves. We saw only one other family while we were there.
Another attraction to head to is the Haunted Mansion. There is a canopy over the queue. And then the attraction is long enough that maybe the rain will stop or slow down once you get out.
We left MK around 6pm to go to FW for Hoop De Doo. We looked a sight!!! We were all wet, messy, and my hair was just crazy from the rain. Let's just say we didn't purchase the pictures!! lol.
Mary