Check the 5 day forecast before you leave and pack accordingly. Not that difficult.

Last I checked the forecast it looked like 60-70's during that time. Some possible showers.

What I want to know is what should I expect the weather to be like during late December in Orlando - comparable to when here? Spring, Fall? Should we bring bathing suits?

I went once in late October and it was gray, kind of cold (light sweater). We have a young child if it matters.