This weekend, Canadians should expect big changes in weather — like the season’s first blizzard — as La Nina returns with the possibility of affecting the upcoming winter.

La Nina is a term referring to unusually cold ocean temperatures in the Equatorial Pacific, per the National Oceanic and Atmospheric Administration (NOAA).

“These cold waters in the Pacific push the jet stream northward. This tends to lead to drought in the southern U.S. and heavy rains and flooding in the Pacific Northwest and Canada,” according to NOAA. “During a La Nina year, winter temperatures are warmer than normal in the South and cooler than normal in the North.”

La Nina is expected to develop over the next couple of months, said Weather Network meteorologist Melinda Singh.

It’s a possibility that most of Eastern Canada will see above seasonal conditions, she said in a video posted to X on Thursday night, while B.C. and the Prairies may see below seasonal conditions.

“But if the coldest air is located in the eastern Pacific, then over 80 per cent of the country could see below seasonal conditions this winter season,” she said.

However, this returning La Nina will be “weak and short-lived” and neutral conditions may return in time for spring, said Singh.