You probably need to pack for a variety of weather.
I am sure especially in the afternoon's you will get pleasant sunny weather probably suitable for shorts/t-shirts etc
However, in the morning's and evening's it will be cooler, so you will need to take some warmer clothing for that too.
We have been 4 times in December and had every weather from warm enough to Sunbathe to Frost on car in mornings. We take more clothes for 10/11 nights in Dec than we do for 25 nights in August.
And it can be cold enough to need coats, hats, scarves, gloves and warm socks. In 1997, there was frost most mornings and it didn't warm up enough to take coats off for about a week.
And it can be cold enough to need coats, hats, scarves, gloves and warm socks. In 1997, there was frost most mornings and it didn't warm up enough to take coats off for about a week.
We were there from 16th Dec to 5th Jan 07 and whilst the weather was warmer than our previous trip requiring hats, scarves and gloves in 2003 we had quite a few rainy afternoons and evenings.
As everyone else has said - be prepared for all types of weather or go with empty suitcases and just buy what you need for the weather that day!
We were there November 30th until December 14th last year. PACK A JUMPER! The weather varied widely. I ended up buying a hat and gloves one night as I was so cold (I am a fat lad so have extra insulation and still needed help keeping my extremities warm).
On the good side you could buy one of the daft character hats (special xmas ones too).
A couple of days were long trouser days.
If you're doing one of the events - Mickeys Very Merry Christmas Party etc - and are going to spend a whole day at the park then take a change of clothes and store them in a locker.
For Christmas in 2005 we would regularly wear t-shirts and shorts much to the amazment on several occasions to the CMs in the parks as they appeared to be freezing.
We have been a few times in December and we always pack a mixture of clothes. The mornings and evenings can be chilly but generally during the day it's warm December is a great time to visit