I was there several years ago (1998, I think) for the taping in early December. I remember that it was one of those December days that get pretty hot out, and that I felt sorry for the people who were being filmed because they had to bundle up in coats to look "Christmas-y". I'm sure that you could watch the parade on TV that year and see lots of folks walking around in t-shirts and shorts!
Oddly enough, cold weather moved in on Monday, leaving a lot of CMs scattered around AK shivering in the early morning fog. It was evidently the first cold snap of the year and they weren't prepared with jackets... they should have borrowed them from those people who were anchoring the parade telecast!