Ontario Weather Review
What will be remembered the most by Ontarians this month? The balmy temperatures. The warmer-than-normal mean temperature trend, which has been the rule since July, remained consistent in December. The entire province experienced mean temperatures exceeding normal values, in some cases by as much as 5.5 degrees. However, the warmer temperatures were not enough to surpass the December mean temperature records set in 2006, when winter went missing.
As for a provincial outlook at total precipitation, Southern Ontario received normal to above-normal amounts, while Northern Ontario was drier than usual. Along with the warm temperatures, a large percentage of the precipitation received this month was in liquid form. A few locations, such as Elliot Lake, London, North Bay, and Waterloo, received more rainfall than normal. Daily rainfall records were broken in a few of those locations, due to the low pressure systems moving across the province around December 4-5 and December 14-15.
Snowfall amounts ranged from below normal to normal. Wiarton and Elliot Lake received about one-third of their normal snowfall totals for December. Sault Ste. Marie’s 2011 snowfall was their second-lowest snowfall total since the 1960s.
Lake-effect snowsquall season arrived in Ontario in December, as usual, although no single event could be compared to the major London and Lambton County snowsqualls of December 2010. A five-day stretch from December 6-10, 2011, saw snowsquall warnings posted for many regions in the lee of the Great Lakes. Muskoka reported 41 centimetres of snow over a three-day period. While the city of Sault Ste. Marie escaped much of the snowsquall activity, areas further north along the Lake Superior shoreline did not.
However, the milder-than-usual temperatures in December did result in lower snowfall accumulations as compared to normal amounts, and few major snowstorms. Instead, there were more frequent freeze/thaw cycles resulting from the passage of cold or warm fronts. On December 15, a flash freeze warning was posted for areas north and west of Lake Superior, with Thunder Bay reporting numerous motor vehicle accidents during the evening rush hour. On December 27-28, flash freeze warnings were posted for numerous regions over both northern and southern Ontario. A strong cold front ushered in a rapid freeze following a warm air mass that had brought showers and temperatures above zero, and 10-15 centimetres of snow accumulations occurred over eastern Ontario.
Freezing rain also made a reappearance over southern Ontario in December, with warnings posted on several occasions: December 13, 21 and 30. Eastern Ontario, including the National Capital Region, was the part of the province which most frequently experienced freezing rain conditions.
Windsor ended the year, as expected, with a record-breaking amount of precipitation for 2011. The total of 1,568.6 millimetres eclipsed the former record set in 1990 by a remarkable 28 per cent.
However, the biggest weather concern for many Ontarians during the middle part of December was the question: “Will it be a green Christmas?” And for many in southern Ontario, it was.
|Location||Mean Temp||Normal||Difference||Warmest since|
|Sault Ste. Marie||-3.0||-6.3||3.3||2006|
|Location||Rainfall||Normal||Difference||Most rain since|
|Location||Snowfall||Normal||Difference||Least snow since|
|Sault Ste. Marie||20.7||80.8||-60.1||1994|
|Sault Ste. Marie||44.6||75.9||-31.3||2010|
Media: For more information, please contact:
Communications Advisor/Media Relations
Environment Canada – Ontario
- Date Modified: