The Weather Network

19 twisters hit Ontario during Canada's worst tornado outbreak

Randi MannDigital Reporter
Published on Aug. 20, 2021, 9:36 AM
Updated on Aug. 20, 2022, 10:16 AM

On the day in weather history, 19 tornadoes occurred in Ontario.

This Day In Weather History is a daily podcast by Chris Mei from The Weather Network, featuring stories about people, communities and events and how weather impacted them.

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On Thursday, Aug. 20, 2009, 19 tornadoes occurred in southern Ontario, making it the largest single-day twister outbreak in Canadian history.

That afternoon, several supercell thunderstorms developed over Michigan, multiplying as they moved into Ontario. At around 3 p.m., the storms quickly strengthened. One storm moved through Ontario over Huron County and into Grey County.

Tornado Damage in Vaughan, Ontario - Courtesy TWN

Tornado damage in Vaughan, Ont. Courtesy of TWN

The first funnel cloud touched down near Durham, causing F2 damage. The next powerful tornado happened near Thornbury, travelling through Clarksburg and Blue Mountain. The tornado also created F2 damage before it moved over Georgian Bay.

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A supercell near Barrie produced four tornadoes, impacting areas near New Lowell, Edenvale, Moonstone, and Ril Lake. Two other tornadoes were observed north of Barrie near Britt and Arnstein.

Tornado Damage in Vaughan, Ontario - Courtesy TWN

Tornado damage in Vaughan, Ont. Courtesy of TWN

A cell formed near the Greater Toronto Area (GTA), just north and east of the city. It spawned a tornado that that travelled through the Royal Riding Academy near Newmarket. Two more tornadoes developed in Vaughan, both creating F2 damage.

The tornado outbreak caused one fatality. The Durham twister passed through a conservation area. At the time, there was a children's day camp in the area. The tornado tossed pieces of a gatehouse and trees into a tent where campers and counsellors were hiding. One child died, and many others received non-life-threatening injuries.

Throughout the entire breakout, around 10 million people in the province were under tornado watches and/or warnings.

To learn more about the southern Ontario tornado outbreak of 2009, listen to today's episode of "This Day In Weather History."

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This Day In Weather History is a daily podcast by The Weather Network that features unique and informative stories from host Chris Mei.

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