I've been wearing Up Jack on a thick undershirt while hiking up in winter Hokkaido, Japan, and it keeps not being too hot nor too cold, as TREW mentioned. The large kangaroo pocket sometimes stores blown snow, but it doesn't causes any problems so far.

This is a great layer for any occasion when it's not super cold out. Packs up great too. The fit is definitely for men. I usually wear a women's large but had to get a small in this and I still roll up the sleeves.

This is a handy layer for skinning up as the name implies. It is light, packs down tiny, breathes well and repels snowfall. I wouldn't use it in drizzle. The kangaroo pocket is surprisingly handy for keeping things out of the snow during transitions. I wish it was offered in other colors.

This is a solid item to have in your backcountry pack or to use on a warm resort day. i also use it when cycling or running or doing other sports in colder weather

I live in this and I love it! I originally bought it for touring on warmer days, but now rock it when I am mountain biking, hiking, or just about anytime I need a light, windproof layer. I wouldn't suggest this as a rain jacket, but it does a pretty great job keeping me dry in light rain or drizzles. I usually wear a size M in women's jackets, and got the Men's S/Women's M size in this for a slightly larger fit. I could probably wear the size down comfortably, but I do prefer the relaxed fit.