My parents lived in Gainesville, FL, and we live in Indiana, so we have loads of experience traveling to Florida in December. Usually, just about anything goes with weather, to be honest. A couple years ago, I bought one of the light weight packable down jackets to bring with me to FL, because we went in December that year, and it was so cold, even with layers and a fleece hoodie, I was not comfortable. But, I didn't want to pack my outside jacket, that would take up my whole suitcase by itself. Almost inevitably, I guess wrong on the weather and either bring things I don't need, or have to buy something that I didn't think I'd be needing (one year, it was a bathing suit). As I recall, it was the same trip that I could have used both the down jacket, which I didn't have yet, and the bathing suit. Have fun!