Well in Cardiff you don't get snow, you get whats technically know as "gritty black slush". It's a natural phenomenon only found here i think. When it falls it's like a cross between rain, hail and sleet and whatever it touches immediatly goes dirty, even if it was a perfectly clean surface prior to the dirty deluge.
But never on christmas day, weather god is nice to us on christmas day. I don't think i can remember one christmas day when the sun hasn't been shining and being perfectly cold and crisp