Pant is thin, but very warm. I tried these out in 30 F weather in northern Michigan, and literally the only other thing I had on my legs were sock and boxer briefs. I didn't wear any base layer and I was more than comfortable all day. I'm sure I could go all day in 10-20 F weather with the right base layer without any problems.These pants give very good mobility. I'm 5'6", 145 lbs so the Medium/Short fit was perfect for me. They are still a little long in that I had to move them out of the way of my trailing binding when locking up at the top of each run so they didn't catch in the binding, but overall a no big deal.