August 20th, 2009 - 1 Day, 1 Province, 19 Tornadoes

On August 20th, 2009, 19 tornadoes touched down in Ontario. This is Ontario's record for most tornadoes in a single day.

On August 20th, 2009, a line of severe thunderstorms swept across Ontario triggering the biggest tornado outbreak in the province’s history.

Four F2 tornadoes touched down, including two in Vaughan, which damaged more than 600 homes. Two other F2 tornadoes struck in Grey County, one at Georgian Peaks Resort near Thornbury, and one in Durham, where an 11-year-old boy was killed.

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Courtesy: Theonlysilentbob/Wikipedia/CC BY-SA 3.0

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WIki Creative Commons: Vaughan Tornado, 2009. Theonlysilentbob. Link:

Courtesy: Theonlysilentbob/Wikipedia/CC BY-SA 3.0

In total, 19 tornadoes were confirmed - a one-day record for the province.

At one point, over 10 million people in southern Ontario - almost one-third of Canada's population at the time - were placed under tornado watches and/or warnings as the storms rolled through.

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On today’s podcast, Chris Mei explains the origin of the tornadoes, how they formed and the track they followed.

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