Take everyone's advice, layer up. It's cold and damp and even northerners come down south and are shocked how cold 45 feels in FL vs where they're from, especially in the wind and being outside most of the day. Most winter days, it usually ends up that the day starts out brisk and by midday, you've warmed up. Pack what you need, gloves, hats, etc. It's totally different being out all day in 40s vs being in 15 degrees and walking to/from your car only. You'll be exposed all day so pack a winter jacket if you have it, hoodies, sweaters, pants, scarf, the works. Don't forget your sunscreen and shades, without the humidity to clog up the atmosphere, the sun can still be pretty intense in the winter even if you're not hot. Keep checking the forecast as I'm sure the cold is still coming but it may vary by a day or so.
Outside of a few really cold days, hopefully it will be pleasant otherwise. Sadly coming to WDW in the "winter" is a mixed bag. It's not like summer where you know you'll always be sweating and experiencing a monsoon everyday. Winter is really a grab bag. I would only change your plans if you are extremely cold weather averse, have a medical condition, etc. Although, as busy as the parks are going to get, you may not have any luck swapping park res days, if you decide to skip the coldest day. I'm not a fan of the cold but if you dress right, you should be ok. Good luck and have fun!
bring a sweatshirt/zip up so you don’t have to buy the overpriced merch (unless you want to of course).
