What is the significance of the winter solstice in Carter's, The Company of Wolves: Short Story?

The solstice serves as a symbol of change. At the beginning of the story, the narrator says that it is Christmas Eve, and that the winter solstice is about to take place. This indicates a seasonal shift, but it also speaks to the shift that will occur both in the story's latter passages, as well as the girl and the wolf's lives.