I think FL weather will be similar to much of TN. If TN weather is variable, so is FL, though FL doesn't have TN's mountains.
You might get a week of warm, you might get a week of cold, you'll probably get a mix.
The one little tidbit I'd add is that FL tends to cool down after dark. We often prefer to add layers after it gets dark in FL during the cooler months. I've seen it rather chilly in November.
Also, don't expect the long term forecast to be correct. Don't expect every day will be ideal swimming weather. If you get a day that's weather nice, carpe diem is a wise approach.