[colebowl]

Living in the Canadian Rockies, we regularly see temperatures in the -20c (-4f) and colder range. I'd highly recommend looking at:

[1] - Outdoor Research - https://outdoorresearch.com [2] - Patagonia - https://patagonia.com [3] - Arc'teryx - https://arcteryx.com

And as others have mentioned, it's all about layering!

[ashtonkem]

I'd also recommend Mountain Hardware. Some of the North Face's more expensive stuff is good too: my sleeping bag comes from them.

Look for companies that are long standing and have good warranties. These companies have good reputations to protect, and are aware that buyers of outdoor gear tend to be very loyal to companies that treat them well. My family personally swore off Columbia after two of their coats failed us catastrophically, for example.