Hi Stacey! It sounds like you are going to have some really excited kiddos! What an amazing way to spend your Christmas holiday.
The weather in Florida can be a bit tricky to predict. The average highs are usually in the low to mid 70’s while the average low’s dip into the mid to low 50’s. I have been to the Walt Disney World Resort in December many times as this is my favorite time to visit. We have had days when we wore shorts and flip flops, and days that I was glad I had my winter coat and mittens. When I pack for Disney in December I actually tend to pack both shorts, T-shirts, and flip flops, but also jeans, long sleeve shirts, and a jacket. If your kids are still in the stroller, I always make sure to have a light blanket that they can snuggle up with on those cooler evenings.
During the winter months, usually either Disney’s Blizzard Beach Water Park or
Disney’s Typhoon Lagoon Water Park are open on a daily basis (they tend to close one of the two water parks for refurbishment during the winter.) The water is heated and we have had some of our best experiences, because crowds tend to be low. I have also seen that they may close the water parks due to un-seasonable cold.
I am hoping that you have a magical and warm vacation! I wish I could see how excited the kids will be when you tell them that they are going to Walt Disney World!
~Heather~