We are just about into December now. In Colorado the weather has only just turned fall/winter like and we've enjoyed a late period of great riding outside. Here's what you should be doing for training right now.
Unless your racing cyclocross or racing in January your training should be relatively low intensity right now. Through November you should have been taking a somewhat unstructured approach to training and logging some longer easy miles. I also encourage my athletes to allow for cross training activities just to keep them mentally fresh. Cross traning, aside from contributing to the rest equation, will also help to rebalance a cyclist since cycling is incredibly sports specific.
Now that we're about to arrive to December 1st it's time to introduce the first elements of intensity. In December you should be starting to do some threshold/ftp work. Duration will start out relatively short, and start increasing as you move through the month. By January 1 you should be feeling fairly comfortable doing efforts up to 30min at threshold/ftp.
Weekends can include some longer group rides with some harder riding but it's my opinion that you should still avoid race type efforts in December. Group rides tend to encourage riding that is harder than necessary so remember what your goals are and reign yourself in if the pace goes through the roof. My advice is to follow wheels and let the other guys flog themselves senseless at the front. Nobody remembers who "won" the winter group ride in March.
With an organized and sensible approach you can enter the 2017 cycling season with your best fitness yet. If you'd like to get your training dialed talking with a knowledgable coach can help you create a plan that works for you.