As much as I am not a fan of the short days and the cold, I really get into training in the winter. Weekends ideally include one long road ride and one super-fun group ride in the woods. Fixed gear on the road during December and January. During the week, I ride right after school in Frost Woods, hit the trainer and rollers, and climb in the gym. If we get enough snow, I break out the snowshoes and trekking poles and beat myself to death with those.
This past December & January I managed just over 75 hours of training, though the weather was superb last winter. We'll see what this year will offer.