I think foxes are forced to venture into places where they would not normally go, when the weather gets colder. The morning we had snow, there was a fox walking up and down my back-garden path looking for food. Unfortunately I did not have my camera to hand and only snapped his tail end in the distance.
A few years ago there was a very good series of documentaries about foxes filmed over a year. Although they are lovely to look at, I think it means serious trouble if they decide to nest and breed in your garden.