Derecho leaves roughly 1,000 km of damage, fatalities in its wake

Digital WritersThe Weather Network
Digital Writers

A damaging derecho swept through southern Ontario and Quebec Saturday, toppling trees and power lines, overturning cars, cutting electricity and even tossing debris through windows. The storms have resulted in at least nine deaths.

A line of powerful thunderstorms rolled through southern Ontario and Quebec on Saturday, leaving behind a widespread trail of destruction.

The storms were set off by a cold front sweeping in, slicing through the heat and humidity that was in place. This resulted in torrential rainfall, hail, frequent lightning, and widespread, damaging wind gusts.

Forecasters are calling the event a derecho — a group of thunderstorms that produces a swath of downburst winds that cause intermittent damage along a path over 600 km long and 100 km wide.

DerechoExplainer (1)

In this case, the damage extended roughly 1,000 km from the Michigan border all the way to Quebec City, Que., hitting the most populated part of the country with damaging wind gusts in excess of 120 km/h, according to Chris Scott, The Weather Network's chief meteorologist.

Here is a breakdown of what occurred in Ontario and Quebec.


A very strong line of thunderstorms developed near Sarnia, Ont., late Saturday morning and tracked northeastward over southern Ontario towards Ottawa in the afternoon.

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At least nine fatalities have now been reported and several have been injured as a result of the fierce winds with the line of thunderstorms. There was also extensive damage to trees, power lines and buildings. There were also overturned cars reported, as well.

Broken window/Tyler Hamilton/TWN

Debris tossed by the powerful wind gusts shattered windows in at least one apartment building. (Tyler Hamilton/The Weather Network)

The winds also led to far-reaching power outages. More than 350,000 customers were without power from this storm Saturday. Thousands remain in the dark as of Sunday morning.

As well, as reported by CBC News, Toronto Police responded to a call for a marine rescue in the area of Lakeshore Boulevard West and Thirty Ninth Street at around 1 p.m. A number of people were rescued and none required hospitalization.

The storm unleashed some extreme wind gusts. Pearson International Airport saw its strongest May wind gust on record after hitting 120 km/h Saturday. It was its fifth strongest wind gust on record. It toppled its previous monthly record of 119 km/h that was documented on May 4, 2018.


Pearson wasn't the only airport to record intense wind gusts. Ottawa International Airport documented its second strongest May wind gust on record, reaching 120 km/h -- its fourth highest of all time.

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Kitchener/Waterloo Airport recorded a 132 km/h gust that could be one of their strongest on record, according to Tyler Hamilton, a meteorologist at The Weather Network. Looking back on earlier totals, a 120 km/h gust was observed on March 30, 1981.

Other notable wind gusts documented include 104 km/h at Brantford airport, 100 km/h in Uxbridge and 110 km/h at Toronto Buttonville airport.

In Uxbridge, considerable damage including overturned vehicles, downed trees and power lines, as well as blown-off roof shingles, was reported after the storm plowed through. As a result of the damaged it suffered, a state of emergency was declared by the town Saturday.

Clarence-Rockland, east of Ottawa, also declared a state of emergency on Saturday.

The Western University-based Northern Tornadoes Project (NTP) visited Uxbridge and southern Ottawa on Sunday to investigate the damage. In an update posted on Twitter Monday morning, NTP said "given the complexity of the damage due to the derecho, it will require thorough analysis in order to classify/rate the event. Work continues."

As well, an NTP survey team will head to the Rawdon, Que., area Monday to investigate damage associated with a tornado-warned supercell that occurred ahead of the derecho.

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Along an axis from Upper Gatineau to Montmagny, intense wind gusts resulted in numerous broken limbs, uprooted trees, damage to buildings and more than 500,000 homes without power. Several roads are blocked due to broken trees. Hail of 2-4 centimetres was also reported.

Peak wind gusts as reported by Environment and Climate Change Canada (ECCC) include 144 km/h at Lake Memphremagog, 128 km/h in Shawinigan, 100 km/h at Quebec City airport and 96 km/h in Trois-Rivières, among others.

See below for a collection of photos and videos of the storm that have surfaced on social media.

Thumbnail courtesy of Sanjay Sekharan/Twitter)