December 2017 Saint Cloud Weather Summary

Roller Coaster Temperature Pattern Pulls December Into Cold Finish

December 2017 St. Cloud Weather Summary

Updated for December Snowfall

The up-and-down temperature pattern that has been typical over the past 3 months continued in St. Cloud during December 2017. The month had averaged 22.3 degrees (high 29.9, low 14.8) through the first 22 days of the month. The month began with the tail end of a warm spell that peaked with a high of 50 degrees on December 4 (within 3 degrees of a record high). There were a couple of brief cold periods with low temperatures in the single digits. However, there were more days with highs above freezing on December 18 and 19.

The brief cold periods in the first two thirds of the month were created by a flow pattern from northwest-to-southeast from central Canada. However, it wasn't that cold since real arctic air hadn't developed in northern Canada. Finally, late in the month, an arctic air mass moved from Greenland into the Northwest Territories, then swooped into both Canada and the US to the east of the Rockies. While that air produced 8 days with a low of zero or colder, and 4 days with a high of zero or colder. This was the longest streak of below zero temperatures since the 4 complete days below zero between December 30, 2013 and January 2, 2014. This included a high of -8 degrees on December 30 (a degree warmer than the record cold high), the coldest high since the -15 high on January 6, 2014, and a low of -24 on December 31, only one of 3 such cold days in the past 4 winters.

Overall, December finished only a degree colder than normal with an average tempeature of 14.9 degrees.

There was a streak of 10 straight days with a low temperature of zero or colder. The most recent streak this long was again during the winter of 2013-2014 with 12 days between December 29, 2013 and January 9, 2014. There was a longer streak of 20 straight days between January 18 and February 6 in 1996. That streak included the last time St. Cloud reached -40 on February 2, 1996. The St. Cloud record for consecutive lows of zero or colder is 37 days between January 17 and February 22 in 1936.

The longest streak of temperatures of zero or colder in recent years was 4 straight days between December 30, 2013 and January 2, 2014. The record in St. Cloud is 8 straight days, set in 1899.

One reason it took so long for cold air to build up even in northern Canada was the general lack of snow cover, even across the Canadian Prairie Provinces. There have been very few major snow-producing storms in the southern Canadian Prairie Provinces and across the Northern Plains. St. Cloud did have 10 days with measurable snowfall in December, but the total was only 4.7inches with only one storm producing more than an inch. Despite an early start (1.4 inch on October 27), there have only been 11.8 inches of snow, nearly 7 inches below average so far this winter.

The total precipitation was only 0.44 inch, only about half of the normal amount.

While the coldest of the cold has eased a bit after New Year's Day, the overall pattern shows a lot of northwest-to-southeast steering flow continuing through much of the week. There is a chance that this relaxes a bit next week, but I don't see the pattern breaking completely through the first two weeks of January.