Recommendations Please

Does anyone have any recommendations for what to wear for the St. Jude Half-Marathon I plan to complete in December. Obviously, I am not sure what the weather will be like at this point but if last year is any indication it will be COLD! I think it was around a high of the mid 30's last year which scares me to death. Strangely enough, I would rather run on a treadmill in a nice air conditioned gym if I had my way, but since I don't I hope to be prepared for the elements. I was thinking something using under armour, but to be honest I don't really have a clue, anyone aware of what I should wear????