Hi Heather,
Thank you for visiting the Disney Parks Moms Panel with your question. We on the panel love helping guests to plan magical Disney vacations! I think that you are smart to be considering both crowds and weather for your trip to
Walt Disney World. Let me offer you some thoughts on the dates that you are considering.
I believe that the crowds will be lower for the December week that you listed. This is because the week in November leads right up to Thanksgiving, so many people will take that whole week off and travel. The December week that you listed ends before Christmas, and as such, many people will not yet be on break and ready to travel. I believe that you are correct, both weeks will be busy, but my guess is that the November week will be less so.
As to swimming, I always say that it is always warm enough for someone to swim in any weather - especially my daughter! In November, the average high temperature in Orlando is 79 degrees Fahrenheit; while in December it is 73 degrees Fahrenheit. While it is obviously cooler in December, Walt Disney World does heat all of the pools, so the water will still be warm. You can bundle up when you get out of the pool and head quickly back to your room!
Either week that you decide, do consider spending an evening at
Mickey's Very Merry Christmas Party. This fun nighttime event at Magic Kingdom allows you to celebrate the winter holidays with special entertainment and treats in a magical setting.
I hope that these thoughts are helpful for you Heather! Have a great time planning your magical vacation, and please do let us know if you have any further questions.