The more the better, that's my motto! But then I'm with Aimiloo on the fashionista front!!! Heeheehee. It only snowed twice in the London suburbs this past winter, but it can get pretty damn cold even without snow I found out!
I lived in a heavy wool pea-coat for several months, but I've also got a ski jacket style thingy for cold rain, a long wool coat for really serious cold, a leather jacket for cold and clear, and a denim jacket and a light rain coat that I've been wearing a lot lately. My biggest coat pet peeve - even when it's cold out it can be boiling in the tube and then you have to either lug around a heavy wool coat or sweat buckets!
If I were being held at gunpoint and told to pick three I'd have the pea coat, a good raincoat big enough to fit sweaters under, and a light summer jacket.