Ontario Weather Review
Forget merely balmy...March 2012 in Ontario was so warm, with so many records being set, that traditional trips south during March break seemed almost superfluous. It was the warmest March on record for many locations and, added to the previous mild months this winter, culminated in a record low snowfall total for the season for Toronto.
New marks were posted across the entire province for the highest mean temperatures, erasing marks that in some cases dated back to the 1940s. Differences from normal values ranged from 5.2 to 8.4°C. Differences to previous records were as high as the additional 3.4°C recorded in Wiarton.
On the precipitation front, northern Ontario was wetter than normal. A new rainfall record was set in Sioux Lookout, surpassing a mark that had stood since 1938. Meanwhile, southern Ontario was drier than normal.
Summary of the warm spell across Ontario
A stationary, abnormally strong high-pressure area across eastern North America was the cause for the historic warm spell across Ontario, which started around March 14. Record temperatures tumbled by the dozen every day.
Some extraordinary examples from this historic event, to convey a sense of its scale:
- It was unprecedented in its duration and scope. It affected all of Eastern Canada, from Manitoba to Nova Scotia, and lasted for upwards of 10 consecutive days. Windsor recorded a full 10 consecutive days of 20 degrees of more. Kitchener had eight days at, or over, 20°C.
- Altogether, close to 250 records were annihilated in Ontario alone, including those broken in a warm spell earlier in the month. It was undoubtedly a record for the most number of records set.
- The maximum temperature of 28.8°C reported in Petawawa on March 21 is the highest temperature ever recorded in Ontario in March.
Many locales surpassed their all-time highest temperatures for a single March day. Several locations even recorded their warmest March day, only to break that mark the next day with an even hotter temperature.
Here are some examples showcasing some new all-time daily maximum temperature records for any March day, the dates they occurred, and previous record values.
|Location||All-time March maximum temperature||Previous record|
|Toronto Pearson||26.0 (March 22, 2012)||25.6 (March 28, 1945; March 28, 1946)|
|Windsor||28.4 (March 21, 2012)||27.0 (March 27, 1998; March 30, 1998)|
|London||27.2 (March 22, 2012)||26.1 (March 24, 1910)|
|Ottawa||27.4 (March 21, 2012)||26.7 (March 29, 1946)|
|Petawawa||28.8 (March 21, 2012)||24.5 (March 30, 1977)|
Daily records were often shattered in a dramatic fashion. For example, Petawawa’s 28.8°C on March 21 was almost 17°C warmer than the previous record on that date.
Preliminary snowfall amounts were compiled for the period of September 2011 to March 2012. Most Ontario locations where snowfall measurements are taken have received a fraction of what they normally receive during the winter season.
For the period of September to March, the Toronto Pearson site received only a third of its normal snowfall values, resulting in a record low snowfall total of 40.4 cm. The previous mark for that period was 52.4 cm, which occurred during the winter of 2009-2010.
|Location||Total snowfall (cm) (Sept. to March)||Normal snowfall (Sept. to March)||Percentage of normal snowfall (%)|
|Sault Ste Marie||225.5||285.1||79|
|Timmins / Connaught||191.2||278.9||69|
While the big weather story in March was the summer-like conditions experienced across much of the province around mid-month, there were some significant storm events as well.
Between the afternoon hours of March 2 and the evening hours of March 3, an intense low-pressure system tracked from the Chicago area through Lake Huron, then into the North Bay area, and then into southwestern Quebec. The system produced a significant snowfall in parts of the Near North. Sault Ste. Marie recorded more than 25 centimetres, while the Greater Sudbury and North Bay areas picked up 15 to 20 centimetres. In southern and eastern Ontario, the biggest impacts were related to strong winds generated by the intensity of the storm system and the passage of a sharp cold front associated with that system. Powerful wind gusts began in the Windsor area during the early morning hours of March 3, with the winds picking up in the Ottawa area later that same morning. Many localities reported wind gusts in the range of 80 to 100 kilometres per hour, with the strongest gust of 113 kilometres per hour recorded at Long Point along the north shore of Lake Erie. The winds caused tree limbs to fall across the area and also caused a number of power outages.
With the mid-month change from winter-like to summer-like conditions, came the return of summer-like severe thunderstorms. On the evening of March 15, a warm front extended from southern Lake Huron to the St. Lawrence Valley in eastern Ontario. That warm front acted as a focus for significant thunderstorm activity across southern Ontario. Between approximately 10 p.m. on March 15 and 6 a.m. on March 16, a series of thunderstorms rolled through the Peterborough area, dumping a significant amount of rain. From available rain gauges in the area, official amounts were only in the 30- to 40-millimetre range, but unofficially the amounts were likely much larger due to the highly localized nature of the heaviest rain. These series of storms caused notable flooding in parts of the city.
|Record high mean temperature readings (in °C), ranked by variation from normal:|
|Location||Mean temp||Normal||Difference||Previous record|
|Pickle Lake||-1.6||-10.0||8.4||-1.6 (2010) (tied)|
|Sioux Lookout||1.2||-7.0||8.2||0.9 (2010)|
|Red Lake||-0.1||-7.7||7.6||-0.1 (2010) (tied)|
|Toronto Pearson||6.7||-0.4||7.1||5.2 (1946)|
|Muskoka||3.3||-3.4||6.7||2.9 (1945, 1946)|
|Ottawa CDA||3.8||-2.4||6.2||2.9 (1946)|
|Toronto City||7.2||1.3||5.9||6.2 (1945)|
|Kingston||4.4||-0.8||5.2||3.0 (1945, 2010)|
|Unusual mean temperature readings (in °C), ranked by variation from normal:|
|Location||Mean temp||Normal||Difference||Warmest since|
|Record high rainfall readings (in mm), ranked by variation from normal:|
|Sioux Lookout||54.6||6.5||48.1||51.8 (1938)|
|Unusual rainfall readings (in mm), ranked by variation from normal:|
|Unusual snowfall readings (in cm), ranked by variation from normal:|
|Unusual precipitation readings (in mm), ranked by variation from normal:|
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Environment Canada – Ontario
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