What constitutes a Christmas song?

I’ve always liked that song, but never thought of it as a Christmas song. I have always associated it with winter though. I very clearly remember the first time I heard it and I was riding in an unheated car on a very cold day (for New Orleans anyway). My guess is that it was released sometime in December of 1988, based on how old I think I was at the time (and thanks to Wikipedia, I see I hit the nail right on the head: 17 December 1988).