Cold start to 2021 expected for Alberta after mild December, Environment Canada says

Alberta's streak of mild weather is expected to stretch into at least the first few weeks of December, but Environment Canada says the province is in for a colder than normal winter come the new year.

The agency's long-range forecast for winter in Western Canada predicts the overall average temperature will be a bit above normal, but that's because it's expected to stay warm in December before a cooler, more seasonal pattern takes over for January and February, says Dan Kulak, a meteorologist with Environment Canada.

"We are expecting a La Niña this winter to be affecting the weather across Western Canada, which does typically bring the colder and snowier winter, especially after the new year, to the Prairie provinces," he said. 

La Niña is the opposite of El Niño, which is characterized by warm waters in the tropical Pacific. La Niña is associated with unusually cool ocean temperatures.

Kulak said La Niña affects the jet stream, bringing about a greater prevalence of colder air across Western Canada.

And while every La Niña season differs, not surprisingly, the farther north you are, the colder it's going to be.

"In that respect, probably Edmonton will have more cold and Calgary will have more spells of warmer weather with the warm westerlies breaking through, than would the central part of the province."

'We might have more periods of snow for Calgary, but overall, it probably will be warmer than Edmonton." 

Kulak says there's a good chance, at least, that the warm spell will let up in time for there to be some snow on the ground for the holidays.

"On average, I would suggest that you should expect a white Christmas in southern Alberta," he said.