You really will be at the luck of the draw regarding weather. We were at DLR near Thanksgiving in 2005, and had a great clear day in the low 70's and it did not get very cold in the evening. We all wore long pants that day, and at least I wished I had shorts on.
However, I would not plan for shorts. Take some shorts, also take long pants, and take sweatshirts - especially ones you can tie around your waist. You might also be prepared to deal with rain.