The action started late Sunday afternoon as a system that dumped up to 30 cm of snow on parts of the Prairies arrived in southern Ontario.
An intense band of precipitation caused temperatures across the region to dip near freezing, meaning many places saw a brief period of heavy snow.
“The same way a heavy thunderstorm can drop temperatures several degrees in the summer, this strong band of precipitation dropped temperatures four or five degrees, so a lot of places saw rain that changed to snow,” explained Rob Davis, a meteorologist at The Weather Network.
Most places got just enough snow to whiten the ground before temperatures rose again with the arrival of a warm front, but some places like Kitchener and London saw 5 cm.
In London, the snow was accompanied by scattered lightning and thunder.
Early Monday morning, it was the GTA's turn for a light show as a thunderstorm rumbled through the area -- the city's first of the year.
Forecasters warned of the potential for more thundershowers through southwestern Ontario as a cold front sweeps by to the south on Monday, but it's the U.S. midwest that is bearing the brunt of the severe weather.
Strong thunderstorms dumped golf-ball sized hail on parts of Kansas and Oklahoma and strong winds snapped trees in half on Sunday, which also happened to be the anniversary of the largest tornado outbreak in history.