It's set around New Years yes. The snow is important since, well for one at least, it explains why the main characters don't just hop on a bus the whole way across the city. Also snow imagery is magical, and that's the kind of theme I'm going for. The timing of New Year is also an important ingredient in the story too. If I describe the book simply in one sentence, I'd say it's Lord of the Rings in a modern city without any literal magic.