I have been a few times the first two weeks of December. Last year I could have worn shorts during the day with pants and a light jacket at night. The previous times were not warm enough (for me) to wear shorts during the day though there were many who did. It was absolutely COLD in the evenings particularly on Friday and Saturday when the park is open until midnight and you are waiting for the parade. It was in the low 40's! We had to purchase extra sweat shirts and wished we had brought heavy coats and long underwear!!!
We will be there again Dec 3-7 and will be prepared for anykind of weather!