News Release
Ontario Weather Review
December 2010
The mean temperatures in Ontario were normal to above normal in December 2010. Above normal temperatures were experienced in the Far North, North of Superior, and in the northeastern part of the province. For most locations, it was the warmest December since 2006. Earlton, north of Temagami, surpassed the record set in 2001 for highest mean temperature for the month by almost four degrees Celsius.
Throughout the month, the different tracks of the systems affecting Ontario resulted in both rainfall and snowfall and the precipitation amounts received varied greatly. Records were broken in Moosonee for most snowfall, while Earlton and Waterloo broke their respective records for least precipitation in December.
Severe Weather
Severe weather in Ontario during the month of December was dominated by two high-impact snow squall events early in the month. During the period December 5 to December 9, cold north-westerly winds flowed over the relatively ice-free waters of Lake Huron and Georgian Bay. These winds showed very little variation during this time, resulting in bands of snow which dumped 75 to 100 centimetres in two particular areas: Grand Bend to London in the flow off Lake Huron and Thornbury to Alliston in the flow off Georgian Bay. In fact one volunteer spotter from Lucan, to the north of London, reported a storm total of over 175 centimetres.
A second high-impact snow squall event occurred on December 13 through to December 14 in the Lambton County area to the east of Sarnia and in portions of Middlesex County, including the city of London. Again, strong northwest winds flowed across Lake Huron and Georgian Bay triggering intense bands of lake-effect snow. The areas impacted by these bands of snow not only had to deal with gusts in excess of 70 kilometres per hour, producing whiteout conditions, but also very cold wind chills. The extreme conditions produced by the combination of snow, blowing snow and wind chill led to hundreds of vehicles and their occupants being stranded along highway 402, which runs between Sarnia and London. It also prompted the counties of Lambton and Middlesex to declare states of emergency as response and recovery efforts were undertaken to rescue the stranded motorists. One fatality was reported as a result of the snow squalls near the town of Ridgetown in the Chatham-Kent area when a motorist apparently left his vehicle, became disoriented and succumbed to the cold.
The snow squall event of December 13 and 14 followed a much larger storm system which affected much of southern Ontario on December 12. This system tracked out of the American Midwest and moved over the lower Great Lakes. Significant snowfall amounts occurred in the area from the Bruce Peninsula up through the North Bay and Sudbury areas where 20 to 40 centimetres fell. However, in the rest of southern Ontario, the precipitation fell mostly as rain. The Ottawa area was the exception as temperatures remained stubbornly below freezing resulting in a number of hours of freezing rain before temperatures managed to climb above the freezing mark.
After a fairly quiet month in northern Ontario, two storm systems moved up from the American Southwest on December 30 and 31. The first system on December 30 and into the afternoon of December 31 provided a general snowfall across northwestern Ontario and areas to the north of Lake Superior, giving accumulations in some areas approaching 15 centimetres. Following closely on the heels of this system, another disturbance moved up from the American Midwest on the evening of December 31, complicating the lives of those who were out to ring in the New Year. This system again gave a general snowfall to the northwest and areas to the north of Lake Superior while, at the same time, providing freezing rain or freezing drizzle for areas to the northeast of Lake Superior into the Kapuskasing area.
Temperature and Precipitation Tables
| Location | Mean Temp | Normal | Difference | Previous Record |
|---|---|---|---|---|
| Earlton | -8.3 | -12.1 | 3.8 | 2001 (-8.6) |
| Location | Mean Temp | Normal | Difference | Coldest since / Warmest since |
|---|---|---|---|---|
| London | -5.0 | -3.0 | -2.0 | 2000 (Coldest since) |
| Moosonee | -8.5 | -16.3 | 7.8 | 2006 (Warmest since) |
| Kapuskasing | -9.7 | -14.3 | 4.6 | 2006 (Warmest since) |
| Timmins | -9.2 | -13.2 | 4.0 | 2006 (Warmest since) |
| Pickle Lake | -14.4 | -17.9 | 3.5 | 2006 (Warmest since) |
| Wawa | -8.1 | -10.3 | 2.2 | 2006 (Warmest since) |
| Chapleau | -9.7 | -11.8 | 2.1 | 2006 (Warmest since) |
| Geraldton | -12.8 | -14.8 | 2.0 | 2006 (Warmest since) |
| Petawawa | -7.4 | -9.4 | 2.0 | 2006 (Warmest since) |
| Location | Rain | Normal | Difference | Least rain since / Most rain since |
|---|---|---|---|---|
| London | 7.9 | 47.0 | -39.1 | 1976 (Least rain since) |
| Windsor | 9.8 | 47.3 | -37.5 | 1976 (Least rain since) |
| Wiarton | 2.0 | 32.4 | -30.4 | 1976 (Least rain since) |
| Toronto | 14.9 | 41.9 | -27.0 | 2000 (Least rain since) |
| Trenton | 72.0 | 46.1 | 25.9 | 2009 (Most rain since) |
| Location | Snowfall | Normal | Difference | Previous Record |
|---|---|---|---|---|
| Moosonee | 207.0 | 39.0 | 168.0 | 1943 (95.3) |
| Location | Snowfall | Normal | Difference | Least snow since / Most snow since |
|---|---|---|---|---|
| Chapleau | 24.8 | 67.2 | -42.4 | 1994 (Least snow since) |
| Wawa | 40.8 | 82.9 | -42.1 | 2006 (Least snow since) |
| Ottawa | 23.4 | 57.2 | -33.8 | 2002 (Least snow since) |
| London | 127.2 | 51.1 | 76.1 | 1977 (Most snow since) |
| North Bay | 87.8 | 61.3 | 26.5 | 2009 (Most snow since) |
| Location | Precipitation | Normal | Difference | Previous Record |
|---|---|---|---|---|
| Waterloo | 30.4 | 73.6 | -43.2 | 1993 (36.4) |
| Earlton | 14.0 | 53.9 | -39.9 | 2009 (18.5) |
| Location | Precipitation | Normal | Difference | Driest since / Wettest since |
|---|---|---|---|---|
| Elliot Lake | 38.0 | 86.5 | -48.5 | 1997 (Driest since) |
| Toronto | 23.0 | 71.0 | -48.0 | 1960 (Driest since) |
| Hamilton | 32.4 | 76.6 | -44.2 | 1995 (Driest since) |
| Chapleau | 23.8 | 66.2 | -42.4 | 1994 (Driest since) |
| Muskoka | 61.8 | 102.3 | -40.5 | 1997 (Driest since) |
| Windsor | 36.8 | 74.7 | -37.9 | 1998 (Driest since) |
| Kingston | 54.6 | 90.4 | -35.8 | 2002 (Driest since) |
| Sault Ste Marie | 40.5 | 75.9 | -35.4 | 2005 (Driest since) |
| Moosonee | 70.0 | 34.7 | 35.3 | 1984 (Wettest since) |
Media: For more information, please contact:
Laurie Thibeault
Communications Advisor
Environment Canada - Ontario
905-336-4711
- Date Modified: