I hibernate, and so does my compost.
I realy, really, really detest cold weather and being cold myself. Usually around December, before the onset of our coldest weather, I flip my compost and put it to sleep for the winter. I secure the lids on with bungee cords and don't look at the compost until the worst of winter is over, around late February or March. By then our weather is generally moderating, and I continue.
By spring I usually have a nice batch of finished compost to spread, and I start over. Until the weather gets really cold the next winter, the process repeats. Most of the time I'll have two batches- old cold pile of materials finishing, and another of actively composting stuff. At some point you have to stop adding to a batch, or it will never "finish".
Karen