Snow and sleet are not the norm, but it is also not rare for temps to drop to freezing or near freezing in Jan and Feb. We usually dress in layers, and pack on the heavy side. You see a few diehards wearing shorts, but most people wear jeans and similar most days. In the early morning and after dark it tends to be fairly cold esp if you are waiting near a lake for fireworks.
This year, WDW was selling their $50 blankets like hotcakes! The Emporium was packed, and almost everyone was buying something warm to wear. Over at Universal, Epic's Dark Universe-themed spirit jersey style shirts were a hot item.
When packing, a good option is to pack extra socks, hats, gloves. they don't take up a ton of space, but they can really help on a cold day. On a day that is cold+rainy a plastic poncho is also great. We almost always pack windbreaker/rain jackets too. Paired with a hoodie they will help keep you dry and warm. (sometimes called a packable parka)
As for hoodies, gotta give a shout out to Roots! They make the BEST hoodies! For a theme park, the full zip style hoodie, oversized, in a dark color is best. Spirit Jerseys can also be a fun option.
While the pools are usually heated, most days are not great pool or water ride weather. Water sloshed all over me on FEA, and it was not fun walking around in wet jeans after that. We only opted to go on Tiana's one day, on what happened to be one of the nicer days, and that was plenty. At night, the ride was empty, as was Ripshaw Falls most days I was at Universal. We did luck out that was nice enough for a short pool visit, but mostly we were in the hot tub.
Bring layers. I also brought some hand warmers which helped on the coldest day. I haven’t looked at forecast for next week. If it is raining be prepared to bundle up because I think it would feel very cold if you end up wet.
