Ontario Weather Review
With the snowy season now over for all but remote parts of Ontario, it can now be said that this season – the period from September 2009 to April 2010 – had remarkably low snowfall amounts in a number of locations:
- It was the winter with the least snowfall ever recorded at the Toronto City site since snowfall observations began in 1843 (46.2 centimetres) and at the Lester B. Pearson International Airport site since snowfall observations began in 1937 (52.4 centimetres). The previous low-snowfall winters occurred in 1952-53 (47.1 centimetres and 53.9 centimetres, respectively).
- Ottawa received 138.2 centimetres of snow. This is much less than normal, although it did not eclipse the lowest amount ever recorded of 131.3 centimetres in 1982-83.
- Locations in the snowbelt, such as Wiarton, received about half the snowfall they normally get during this period. Wiarton received 228.8 centimetres compared with a normal 425.4 centimetres.
- Thunder Bay received 52 centimetres – less than a third of what would be expected during a normal snowfall season (185.8 centimetres).
- There were numerous locations in Northern Ontario that broke records for lowest seasonal snowfalls.
- Windsor’s snowfall (112.9 centimetres) was within its average range. What is surprising is not the actual amount, but that this total is much greater than what other locations such as Toronto received over the same period.
April was characterized by warmer temperatures than normal and drier conditions for most locations. Across the province, mean temperatures for April were warmer than normal by at least 2.5°C. Record values for mean temperatures from the 1950s, 1980s, and 1990s were either reached or surpassed. There was also a heat wave during the Easter weekend. The early part of the weekend reported numerous daily maximum temperature records broken for many parts of the province.
In terms of April precipitation, most Ontario locations, except for the northwestern part of the province, received less than normal.
The transition from a mild winter to a benign and warm spring continued for much of the month across the province. The notable exception was a strong storm system that moved up from the American Midwest during the early morning hours of April 8, serving as a reminder that winter weather in April is far from uncommon. By the time the storm system finally pulled out of Northeastern Ontario in the early morning hours of April 9, a large swath of Central and Northeastern Ontario had been impacted by freezing rain or snow. Total accumulations of snow from the system were in the 15-centimetre range in places like Chapleau, Timmins and Kapuskasing. In locations such as Sudbury, North Bay and Earlton, the main weather element was freezing rain, which at times became a messy mix of freezing rain plus ice pellets and snow.
Another large, intense low pressure area moved over the far north of Ontario on April 16, bringing a wintry mix of freezing rain, ice pellets, and snow and blowing snow to these localities. Gusty north winds associated with this storm occasionally attained speeds of 70 kilometres per hour.
April normally heralds the beginning of the severe thunderstorm season in Southern Ontario, as the first of the warm and humid air masses make their way northward. These air masses act as the fuel that can drive thunderstorm formation. Historically, the month has a few powerful storms that produce large hail, damaging winds or tornadoes. While there were a few strong thunderstorms that resulted in severe thunderstorm warnings being issued for portions of Southwestern Ontario on April 6 and 7, there was no significant damage reported from these storms. After that, the weather again settled down with no further strong thunderstorms occurring.
|Record high mean temperature readings (in degrees), ranked by variation from normal:|
|Location||Mean Temp||Normal||Difference from normal||Previous record|
|Pickle Lake||5.7||0.4||5.3||1987 (5.7)|
|Toronto Pearson||10.5||6.3||4.2||1955 (9.5)|
|North Bay||7.5||3.3||4.2||1987 (7.5)|
|Sault Ste. Marie||7.1||3.1||4.0||1987 (6.9)|
|Toronto City||11.4||7.6||3.8||1955 (10.5)|
|Waterloo||9.2||5.8||3.4||1987, 1991 (8.1)|
|Thunder Bay||6.2||2.9||3.3||1987 (6.1)|
|Unusual mean temperature readings (in degrees), ranked by variation from normal:|
|Location||Mean Temp||Normal||Difference from normal||Warmest since|
|Unusual rainfall readings (in millimetres), ranked by variation from normal:|
|Location||Rainfall||Normal||Difference from normal||Least since|
|Sault Ste. Marie||24.2||50.5||-26.3||2000|
|Location||Rainfall||Normal||Difference from normal||Most since|
|Record low precipitation readings (in millimetres), ranked by variation from normal:|
|Location||Precipitation||Normal||Difference from normal||Previous record|
|Unusual precipitation readings (in millimetres), ranked by variation from normal:|
|Location||Precipitation||Normal||Difference from normal||Driest since|
|Sault Ste. Marie||41.1||68.5||-27.4||2009|
|Location||Precipitation||Normal||Difference from normal||Wettest since|
|Significant seasonal snowfall statistics, September 2009-April 2010|
|Record low snowfall readings (in centimetres), ranked by variation from normal:|
|Sault Ste. Marie||166.1||302.5||-136.4||188.4 (1982-83)|
|Thunder Bay||52.0||185.8||-133.8||57.4 (2002-03)|
|Sioux Lookout||86.9||199.0||-112.1||128.9 (1982-83)|
|Red Lake||80.6||187.3||-106.7||85.9 (1943-44)|
|Toronto City||46.2||133.1||-86.9||44.8 (1952-53)|
|Waterloo Wellington||74.9||159.4||-84.5||77.8 (1982-83)|
|Toronto Pearson||52.4||115.4||-63.0||53.9 (1952-53)|
|Unusual snowfall readings (in centimetres), ranked by variation from normal (100 cm or more):|
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- Date Modified: