Since the weather in January can be unpredictable, pack for anything! We went last January and the beginning of the week was cold!(highs in the 40's). But it did warm up so you have to be prepared. Bring layers. We found that mostly we wore jeans, a t-shirt, a sweatshirt over that, then a fleece jacket over that. As the day goes on you can usually peel off a layer or two. At night it was pretty cold. We even had the kids in hats and mittens to watch the electric light parade. But believe it or not, we were able to use the pool on our trip. Our warmest days were about 65, but the pool was heated so we would jump in and have fun, then RUN back to the room! I have heard though that you can hit highs in the 80's in January too. So I would recommend watching the forecast as your trip gets closer, but have everything on hand ready to pack (bathing suit, shorts, sweatshirts, fleece, mittens). Our suitcases weighed a ton, but for a trip at that time of year, we were prepared. I would say the fleece was the most practical item we brought, just perfect for what we hit.