Canadians hoping for a white Christmas this year may see both snow and frigid temperatures. Some weather models indicate conditions favorable for snowfall, but this is linked to the Arctic polar vortex, which could lead to extremely cold weather this holiday season.

Andrej Flis, a weather researcher from Severe Weather Europe, analyzed data from the European Centre for Medium-Range Weather Forecasts and the Global Forecast System. He noted an atmospheric warming event in late November that could push frigid polar air southward in mid-December, potentially lasting for up to two weeks.

The polar vortex, a swirling mass of cold winds, is a normal part of the Earth's climate, similar to its counterpart over Antarctica. During winter, as the vortex strengthens, the polar jet stream shifts northward. Flis explained that a high-pressure anomaly near the pole could trigger a sudden stratospheric warming (SSW) event, where temperatures in the stratosphere rise significantly. This disruption can alter the jet stream's shape, allowing colder air to move into regions of Canada and the U.S. that typically experience milder weather.

Flis pointed out that this year's timing is earlier than usual, recalling similar patterns from last January and March, although the latter had less severe weather. David Phillips, senior climatologist emeritus with Environment Canada, described the expected cold as “extra cold, it’s got a duration to it and it’s crisp.” He added, “It doesn’t even have to set a record; it’s just so bone-chilling cold that everything kind of stops.”

While Flis is cautious about his predictions, he noted that not all SSW events lead to cold and snowy conditions at the surface. Phillips acknowledged the reliability of the models Flis used, stating, “this is about as good as science gets for something like this so far in advance.” He emphasized that weather patterns can vary, and the current situation may have its own unique characteristics.

Factors such as warming temperatures in Canada and whether the continent is experiencing a La Niña or El Niño year also play a role. Phillips mentioned that climate change has made these patterns less predictable in recent years. The upcoming winter is expected to be influenced by La Niña, which typically brings colder temperatures and increased snowfall, particularly in Western Canada and the eastern regions.

It remains uncertain where the polar vortex's effects will be felt most in Canada. Flis anticipates a northerly flow from Western Canada moving into the U.S. and gradually spreading eastward. He humorously noted, “It doesn’t stop at the border. There are no tariffs on this kind of thing,” suggesting that “Americans will blame Canada” for the cold snap.

Phillips cautioned that even if this cold spell occurs in December, it does not rule out further cold events in January or February. “Sometimes we could have two or three,” he said. He also clarified that not every prolonged snowfall is linked to the polar vortex, as cold air can travel on the jet stream and cause temporary freezing conditions.