January is almost always the coldest month in this part of the world. If one wants cold, perhaps “patience” is the key word. Temperatures became “normal” around mid-month, cold enough for most people, especially with windy conditions. Then, a week later, serious cold sets in.
In some ways it was convenient, -40 is -40, whether one speaks Fahrenheit or Celsius. Blame this on an Arctic vortex, a persistent large-scale low-pressure circulation pattern that produces a funnel of cold air that reaches thousands of miles/kilometres to the south. There was a break, but a similar pattern re-established late in January and has persisted into February with temperatures slowly heading towards a possible February thaw.