The Northern Tornadoes Project says a twister that touched down last month in Malden Centre was the country's first in 2024.
The EF-1 tornado tied the record for the earliest tornado ever recorded in Ontario. Another one in Clifford also touched down on March 16, eight years ago.
The project based at Western University in London says the tornado ripped the roof off a "well-anchored, double-wide mobile home" and brought down trees in a woodlot along its track.
Maximum wind speeds reached 150 km/h.
"Radar evidence from the nearby tower Doppler radar at Detroit Metro Airport clearly shows an area of tight rotation in the exact location where the damage occurred," said the project in a blog post.
A storm at the time generated severe hail, but no tornado warning was issued.
The Northern Tornadoes Project received photo evidence of the tornado on Saturday.