The waterspout formed between 3 and 3:30 p.m. on Wednesday as a squall line brushed past south of Lake Erie.
No injuries or damages were reported, but the large spout was a dramatic sight for weather-watches on both sides of the border.
On Tuesday, Environment Canada had issued a waterspout watch for the Canadian portion of Lake Ontario and the Ontario portion of the St. Lawrence River as a cold front created ripe conditions for thunderstorms.
Wednesday was drier and calmer in southern Ontario, but waterspouts can form at the tail end of squall lines, says Gina Ressler, a meteorologist at The Weather Network.
“The southernmost cell of a squall line can often strengthen and have more rotation because there are no cells behind it to impede the southerly flow,” she explains. “We call these 'bookend vortices.'”
Earlier in the week, Environment Canada issued a special weather statement calling for the risk of weak funnel clouds over land.
The Weather Network's Stormline was flooded with calls reporting funnel clouds west of Kitchener on Monday. One viewer said the funnels looked out of place on such a calm day.
TWN meteorologists say it was a fluke that the funnel clouds occurred on a day with little active weather in the forecast.
There just happened to be enough spin in the atmosphere combined with updrafts.
Severe weather moved into southern Ontario on Tuesday, with heavy downpours causing localized flooding.
With files from Andrea Stockton and Sana Ahmed