Hi Joan

Welcome to the forum!

The weather is usually around 70F or so but it sometimes gets cold in the evenings so you'll need jackets.

Christmas is wonderful in Florida but the decorations usually come down the first weekend after New Year so make sure you fit all these in before then.

Queues/lines at the parks shouldn't be too bad, particularly after New Year weekend as that usually marks the end of everyone else's holidays but you'll have the advantage of still being there!

Have a great time!