I will be sending pixie dust your way for good weather!
I was there Dec. 7 -15, last year and it POURED day and night almost the whole time. We had about two days were it did not rain. We had 4 kids with us, one in a stroller. We did not let the rain stop us though. Just used a lot of ponchos. I bought them before I left because I like the men's size. I find it to be bigger and they cover the arms more than the ones you can buy at the parks. It poured so hard they had to cancel Mickeys x-mas parade one night. Luckily it was not the night I was there. But they did let those people back on another night.
Have a good time reguardless of the weather!!!!