Layering is the answer. I have a LL Bean down coat with a hood that was good to -50F when I lived in Alaska. All well and good until you warm up after a trip to the mailbox. Layer! I use a Patagonia base layer, Marmot fleece jacket with hoodie and overlay those with a Northface gortex shell. Good to at least -20F if you keep moving. Patagonia is the best though. Unbeatable on any level.