I've been there many times in Dec, Jan, and Feb. During those months you just never know that the weather is going to do. Some trips I have worn shorts and swam all week, some trips I have worn coats, gloves, scarves, and hats and still froze, and then other trips the trip would be warm enough for shorts a few days, then a few days later I'd be in jeans and long sleeves. What I always do is get out enough clothes for either scenario, then just a few days before we leave, check accuweather.com and pack appropriately. However, even then I carry a little of everything. One trip accuweather was calling for warm temps all week, so all I packed was shorts. An unexpected cold front blew through and we had to buy sweatshirts and gloves and almost froze. Now if the weather is calling for warmer weather I'll pack shorts and T's, but then throw in one pair of jeans and a sweatshirt, as well as a pair of thin gloves. If it's calling for cold weather, I'll still pack a couple pairs of shorts and one swim suit, just in case. Winter in Florida is the toughest time of the year to pack for because it can change so drastically from one day to the next. I've worn shorts and coats on the same trip more than once.