Can you try a hybrid commute on the days that aren't too bad? Is there a halfway point you can stash your car and ride the rest of the way? Are you flexible enough to be able to make a game time decision? If so, maybe decide to ride if the temp is above a certain threshold. Then there's no "do I or don't I?

I am lucky to only have a 4 mile commute. My rule in the winter is that I ride if it is at least 35 and I don't ride if it is less than 30 (because that generally means ice in these parts). Between 30 and 35 depends on how wet and/or icy it is. But at least if it is 35, I'm on the bike.

Good luck!