A cavalcade of Colorado lows can send Canada’s forecast into upheaval

Feel seasick looking at the extreme temperature swings in your forecast this time of year? You’re not alone.

Warm today, cold tomorrow, more warmth, followed by snow, then a risk for thunderstorms...what in the world is going on with the forecast?

The wild ups and downs of springtime weather happen every year, but it’s always a shock to the system to see so many different conditions in quick succession.

This is arguably the most volatile time of the year for the weather in Canada, especially across the eastern half of the country.

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Warmer temperatures south of the border are steadily creeping north, a migration that’s forcing the jet stream deeper into the heart of Canada.


Low-pressure systems that tracked south of the Great Lakes in winter are trekking farther north with the jet stream, pushing snow deeper into the forests of northern Ontario and Quebec while highly changeable conditions prevail across the south.

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One particularly spry Colorado low can bring a whole spectrum of weather to a community over the span of a single day.

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A robust low-pressure system churns up the atmosphere like a blender. Strong winds blowing around the storm drag warmer temperatures up from the south and pull chilly air down from the north.

For much of Ontario and Quebec, your first experience with a classic Colorado low could be an unusually warm day—or even an icy mess.


Southerly winds ahead of these lows can force temperatures to spike ahead of the storm. If there’s cold air already settled in at the surface, a period of freezing rain or ice pellets may occur before temperatures rise above the zero-degree mark. Thunderstorms are even possible in this warm sector.

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When the cold front comes through, temperatures can plummet and force rain to change over to snow in a matter of minutes. Bands of lake-effect snow are also possible as this chilly air filters over the unfrozen lakes.


If you get more than one of these storms in a week, forget being a tired cliché—a graph of temperatures for the week really can look like the outline of a thrilling rollercoaster, and that doesn’t factor in the lurches between rain, snow, and everything in between.

While some years see more volatile weather than others, every March and April experience this seesaw between cold and warm, rain and snow, and even the odd rumble of unexpected thunder. It’s the natural outcome of the rocky battle between winter hanging tough against summer’s inevitable arrival.

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