British Columbia and the Prairies had better prepare for an unwelcome house guest to move in for the winter, forecasters say.

Meteorologists are calling for an early and cold winter in Western Canada, probably one of the top three coldest in the last 20 years for the West Coast.

AccuWeather.com weather expert Brett Anderson said western provinces can expect a fifth-consecutive deep freeze to move in and stay.

For the rest of Canada, including the Greater Toronto Area and St. Lawrence Valley, it's expected to be business as usual with typical winter weather patterns in place most of the season.

"However, I do expect one or two major snowstorms to affect the region," Anderson said on the website.

Ontario and the Montreal area will be hit with a couple of Arctic blasts throughout the winter and several hard-hitting snowstorms, but temperatures will be above normal overall, he said.

"That's typical of a La Nina, but (blasts) don't last very long; they come and they go," he said.

La Nina is an event that takes place when the sea surface cools across the eastern Pacific near the equator. It can affect the jet stream, bringing icy blasts from the north into the western regions of Canada.

The effect is expected to be moderate this year, Anderson says.

Another AccuWeather meteorologist, Jack Boston, told the Winnipeg Free Press Manitobans can expect beautiful fall weather to change suddenly, predicting a slight chance of snow in the coming week and accumulating snow by Halloween.

Temperatures will be about two degrees below normal, he told the newspaper, noting the province will likely receive less snow.

But temperatures will be five degrees below normal across other western provinces, meaning the thermometer could dip below zero in Vancouver.

On the East Coast it will be drier than normal in Newfoundland and Labrador and slightly colder. Other parts of the East will see a normal winter, with southern areas a little less cold.

As for the Arctic, the perennial source of winter blasts, it's expected to be normal, not that that's any cause for celebration.

(Getty Images)