Coldest final week of December in over 80 years. Frigid weather eases as we head into January

It was a frigid end to December over much of the continent, including throughout the Prairies and southern Manitoba. In Winnipeg, the final week of the month averaged a bone-chilling -27.7C, the coldest final week of December since 1933, and the 4th coldest since records began in 1872. 

The frigid finish to December was in stark contrast to the first 3 weeks of the month which were milder than normal. In fact, through Dec 23rd, December was averaging about 3C above normal (-10C vs -13C)  But that all changed by Christmas Eve as frigid temperatures moved in for the holidays with temperatures averaging over 10C below normal between Christmas and New Year's Eve. As a result, December ended up about 1.5C below normal in Winnipeg with a mean temperature of -14.8C  (vs the December "normal" of -13.2C)  

December 2017 in Winnipeg. Very cold finish
spoiled an otherwise mild month  

Luckily, the massive Arctic airmass that has plagued much of North America over the past week has retreated for the beginning of January with temperatures rising to normal values in southern MB, and even above freezing in Alberta, which had seen temperatures of -40C just a couple days ago. Colder weather will prevail through this week (but not like last week), before another moderating trend sets in next weekend with temperatures near or above normal over southern Manitoba. Seasonably cold weather is expected next week.  Mid January marks the coldest time of the year on average in southern MB with normal highs of -13C and lows of -23C for Winnipeg. Daily averages slowly climb through the latter half of January rising 2C by Feb 1st.