It is GREAT for cold weather, seriously. Here's a tip our trekking guide gave us and it completely changed my experience. This bags work with your own body heat, so when you get into your tent, take your clothes off and snuggle in. The first night on top of Mount Roraima I got inside of it with my cold weather pijamas and two pair of socks and I felt like my feet were going to fall off. Second night, after he told us this, I slept with nothing but my underwear on and at some point I had to take off the blanket because I felt it was getting too warm. I couldn't believe how when I had to go out it was sooo cold, while I was com warm and comfy inside.
Valeria Bonilla