I live in Lake Tahoe, and that is about the temp of my morning commute every day in the winter. The coldest I have had this year was -2, but normally it's in the teens. I wear the following: Cycling shoes with full neoprene covers, wool socks, wool thermal bottoms with a pair of wind pants over the top, wicking t- shirt with a wool shirt over the top, and then a wool sweater followed by a thin cycling wind breaker...Turtle fur balaclava, shop tinted glasses (sunglasses for the cheap), and a pair of thick wind proof fleece gloves with thin work gloves over the top. I am always warm after the first hill, and usually I have to pace myself near the end of the commute on the last hill to keep from overheating. My friends think I am crazy, but I am very comfortable, and the air is crisp and fresh at those temps.
Good luck, and enjoy the ride!