My coldest was -2F just a couple of weeks ago. Compared to my previous coldest ride of 0F, back when I had substandard gear, this more recent ride was quite comfortable. In fact, I have yet to get to work during the coldest days this season without my outer jacket unzipped to ward of sweating. I think I can go much colder without adjustment to anything except another layer for the feet -- bootie type covers.

By the way, I wear sandals year round because they are by far the most versitile footwear I've found.