Grandma, you'll find the weather is pretty unpredictable for swimming in January. Some winters it's a little cool for Florida residents but absolutely tropical for snow bunnies from Michigan. If that's the case, you'll do fine in the heated pools as long as you have a fluffy wrap for when you get out. But once in a while there is a Florida Freeze when the weather dips slightly below freezing. On those days, the only visitors in the pool come from northern Canada! My advice is to watch the long-term weather forecast as your trip approaches, and pack accordingly.