I have had some truly crappy commutes that did not involve temperatures that were even remotely as cold... add some freezing rain and wind and I can barely stay warm.

Give me -15 C and dry and I will be a happy man.

To add to the previous, the base temperature was -52 F and with the wind chill the temperature was something like -61 although when you are on a bike and completely covered this is not a factor, it is pedestrians and people on the street that are hard core as frostbite can happen in seconds at these temperatures.

I certainly would not ride for fun in this kind of weather although I once took my road bike out for a test ride on a dry clear night when it was -40. Was not wearing anything more than I needed to prevent frostbite on my face and hands and only rode a few miles before I realized someone would have to pry my hands off the bars.