Don't worry about the cold.
The mean January temperature where I live is -15 C. (5 F.) so we are frequently as cold or colder than you are, especially overnight. For example, our coldest day in December was -44 C. (-47.2 F.), and guess what: my bees are just fine. It isn't the cold that hurts them; it is the lack of ventillation and/or of food. As Beemaster says, as long as they are out of the wind, they'll be fine.
My hives are surrounded by a thick, high cedar hedge to cut the wind. I wrap my hives loosely with old carpeting with the nap to the inside and flaps cut out for the reduced entrance and for the upper vent. I also build snow up around the boxes as this is a very good insulator. It works like an igloo. Have you ever read any Jack London?
Check out my link (below) to a webcam of our parliament. Today it is a balmy -15 C. (10 F.) Great for skiing!