This January, the Arctic tap has been left wide open, sending a frigid chill as far south as the Gulf of Mexico and even Cuba to kick off 2025.
But for the week ahead, many Canadians will catch a break as milder Pacific air sweeps across the country, bringing above-normal temperatures. Enjoy it while it lasts—because the Arctic is plotting its next move.
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A powerful pattern is setting the stage for an amplified jet stream that will shunt cold air south, and the roots of this shift lie thousands of kilometres away in Japan.
Upper-level pattern Monday, Jan. 13
Arctic keys falling into place
In the western Pacific Ocean, a pronounced trough is forming near Japan. As this system migrates across the Pacific, it will amplify a towering ridge over Alaska by late this week, fuelled by a roaring jet streak slicing across the ocean.
This setup is driving the East Pacific Oscillation (EPO) sharply into negative territory––a high-confidence signal for colder air plunging southward across the North American continent.
Upper-level pattern Friday, Jan. 17
Once the ridge of high pressure establishes itself across Alaska, downstream is where things get interesting.
Deepening trough and building cold
Currently, the core of the stratospheric polar vortex is swirling over portions of Nunavut. However, as the polar vortex stretches in the coming week, it will extend its icy grip across the Prairies, Hudson Bay, spreading east into Ontario and Quebec.
With the Arctic air’s density and the evolving jet stream pattern, there’s even the potential for bitter cold to blanket nearly all of Canada, coast-to-coast, even if only briefly.
Saturday, Jan. 18, temperature pattern Canada
U.S. Arctic express
The cold air won’t stop at the Canadian border.
This Arctic outbreak is poised to push deep into the United States, significantly heightening winter weather risks once again in the southern states over the next couple of weeks.
Monday, Jan. 20 national temperature pattern Canada
Great Lakes rapid freeze-up
In just six days, Great Lakes ice cover has surged by an astonishing 500 per cent, a testament to the frigid air’s grip.
If this Arctic air mass materializes as forecast, we may see Great Lakes ice coverage approach seasonal averages for this time of year.
Current Great Lakes ice coverage_Jan. 11, 2025
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