Hello, Lori!
Not to worry! We've used the pools at multiple resorts throughout the year; they are very nicely heated, so if you'd like to swim, you'll most likely be just fine.
Of course, if there is a cold snap, it will be quite chilly OUT of the water, but such events happen more often a bit later than mid-December. We were in Walt Disney World last December (mid-month) and the weather was gorgeous! No jackets needed, even at night. According to weather.com, December highs average around 72 and lows are 51; add in a
heated pool and swimming will be a welcome treat!
Disney's Beach Club Resort is a spectacular property, with a location that can't be beat and amenities that will truly spoil you. Enjoy your stay!
Send more questions as you think of them; we love to help!