ach buda what's -1?! Come on now -15 and you can wear jeans! Actually when it's -15 I don't leave the house.
I wear skirts in winter. It's no big deal if you're just getting out of a car and into a building. I don't wander round parks in them though. But I don't wander about much fullstop in winter.
In my case, wearing skirts came from going out with Russian men. They will fawn all over you all day, buying you flowers, opening doors, combing your hair and all sorts of weird things like that if you wear a skirt. If you wear jeans they don't.
So I got into the habit. Apparently even in winter in Russia women manage to wear skirts all day. Dunno how though.