We usually go in January too. Same experiences as those posting ahead of me. Only one year was it "chilly" the whole trip, and that was because it was damp. I find it usually averages out to about mid 60's -mid 70's most of the time. Last year it was in the 80's most often. In 1999, we had two days of damp 40's , and layers were essential. We usually pack one pair of shorts, two pairs of jeans, a sweat shirt and a few shirts and blouses to layer. I tend to wash once a day, so we don't need a LOT of extra clothes. We usually have a Disney jacket with us since we are returning to cold weather at home, and will need it when we get off the plane there. I also make sure I stick one of those little stretchy pair of gloves in for those chilly evenings when we are sitting at Illuminations or Fantasmic.