Zeraph

So I've been wanting a really toasty winter coat for awhile now, but find myself lacking information. I'm in a warm area, so I grew up knowing little about a good coat. Occasionally I find myself camping in a situation where it gets really cold. My last trip I was sleeping in a sub 0 sleeping bag, my sweats, two comforters, and an air mattress and was still cold! So I want to know about the warmest possible coats. Is synthetic the warmest? Or maybe wool?

Thanks