The weather at this time of the year is completely unpredictable in Central Florida. There are days in Nov/Dec/Jan when I have used both the heater and the air conditioner in my car in the same day!! Today it was in the mid 80's...very warm. By the weekend, it is supposed to be in the 70's with a lot less humidity. Sure you can swim and you will see a lot of people from up north in the pools! Would I swim in this weather, no, but I live here and can swim in the summer when it is absolutely unbearable! However if it does drop into the 60s during the day, you probably aren't going to want to be swimming.

Wish we could predict the weather here at this time of year, but it's virtually impossible. I'll keep my fingers crossed for your trip
Take care.