In the Catholic Church, Epiphany is always celebrated the first Sunday after New Year's. Secularly, though, it seems to me the "winter festival" runs pretty much the whole of December. Christmas Day itself is often an anticlimax for me, especially since I have a new holiday tradition: being sick on Christmas. But the "festival" aspect goes on till New Year's, with parties and such. You're right, though: it's sad to see it all go away, especially knowing that it's to be followed by deep winter.

Ah well, at least we have Arisia to look forward to.