For colder climates, it's important to actually invest in quality knits. Vince has one of the most soft and light weight knits out there on the market and although they're not as popular as some of the more trendy brands, they're definitely modern and timeless. This sweater is made of a blend of wool and cashmere so although it's as thin as a H&M sweater, it packs way more warmth. That's why I was able to get away with wearing a Nasty Gal cardigan in the cold.
On another note, when packing for a trip to the snow, I highly recommend these boots from Amazon. They're light, warm and waterproof. However, I did waterproof spray them (just in case) before going in the snow that was knee high. My boots kept me dry and since I was only going to wear these a few times, they were definitely worth it. Nobody likes cold wet socks.
What are your favorite sweater brands that keep you warm?