After coldest December temperature in Winnipeg in 40 years.. a big, but temporary, warm-up on the way Monday..

Minimum temperatures (C)
Sunday Dec 15 2013
Record lows over much of MB

An arctic ridge of high pressure sprawled across Manitoba Saturday night brought some record cold temperatures early Sunday with temperatures plummeting to the -35 to -40C range over southern Manitoba, and -43C in Thompson. In Winnipeg, the thermometer at Winnipeg airport bottomed out at -37.3C Sunday morning, setting a new record low for Dec 15th, eclipsing the previous record of -37.2C set way back in 1879. (records began in 1872) For Winnipeg, it was the coldest December reading in 40 years, since a -37.8C reading on December 31 1973. That -37.8C reading, tied on Dec 31 1967, stand as the coldest temperatures ever recorded at Winnipeg airport in the month of December since records began there in 1938. However, previous to 1938, much colder temperatures have been recorded in Winnipeg in December at the former weather observing site at St John's College which took weather observations from 1872 to 1938. This included Winnipeg's all time coldest temperature during a remarkable cold snap in December 1879 that saw the temperature plummet to a record low of -47.8C on Dec 24 1879. The high that day was only -39.4C, making it the coldest day in Winnipeg history since records began in 1872.  By the way, the last time a reading of -40C or lower was recorded in December in Winnipeg was December 28 1933 with a low of -41.1C.

Coldest December temperatures in Winnipeg over the past 50 years  (since 1963)

Dec 31 1973 ............. -37.8C
Dec 31 1967 ............. -37.8C
Dec 15 2013 ............. -37.3C
Dec  24 1996 ............ -37.0C
Dec 12 1995 ............. -37.0C
Dec 20 1989 ............. -37.0C 

But enough about the cold.

Temperature map valid 1 pm Sunday Dec 15th 2013
Note large wave of mild air over western Canada
poised to spread east over the next 24 hours 

The frigid cold snap which has been locked over Manitoba for the past 10 days, will finally break Monday as a warm front from western Canada moves east and spreads a westerly flow of milder Pacific air across southern Manitoba. This will allow temperatures in Winnipeg to climb into the minus single digits Monday afternoon for the first time in two weeks. Note however, that in advance of the warmup, a band of snow ahead of the warm front will push into Winnipeg and the Red River valley by late Sunday afternoon giving a few hours of snow through the evening. 2-4 cm is possible along with reduced visibilities in blowing snow as southerly winds increase through the evening.

The milder weather is expected to last into Tuesday, but unfortunately it doesn't look like this will be a sustained warmup. Another clipper is expected by midweek with more snow (possibly another 2 to 5 cm), followed by a reinforcing shot of Arctic air by the end of the week into next weekend that will send temperatures back well below normal over southern Manitoba through the Christmas holidays. So enjoy the next couple of days of relief while you can!

Temperature trace from Rob's Obs weather station
Charleswood, Winnipeg - Dec 16 2013
showing dramatic temp rise from Sunday morning

UPDATE: Dec 16 2013
Temperature rises to -1.9C at YWG airport Monday afternoon, a phenomenal rise of over 35C within 30 hours from Sunday morning's low of -37.3C. The graph left shows the dramatic temperature rise as measured at my backyard weather station in SW Winnipeg. Note the steeper temperature rise around noon when winds shifted into the west and tapped the mild Pacific airmass.