Punxsutawney's official groundhog handlers hoist Phil in the air following his prediction. Photograph: Jason Cohn/Reuters

As Britain was buried under snow this morning, some of North America's top furry, four-legged meteorologists shrugged off their winter's sleep and crept into a sunny morning, portending six more weeks of cold weather.

In the US and Canada today, thousands gathered to observe Groundhog Day, on which otherwise serious-minded people and news organisations claim to foretell the remaining length of winter by whether a groundhog sees its shadow at sunrise.

According to the folk tradition, which dates back centuries in Europe, the weather on a certain midwinter day foretells either the imminent arrival of spring or its delay another six weeks.

This morning in Punxsutawney, Pennsylvania, a small town about 65 miles northeast of Pittsburgh, a crowd of more than 13,000 gathered to watch the top-hatted members of the town's Groundhog Club channel the beast's prediction of six more weeks of winter.

Top Canadian groundhogs Wiarton Willie of Wiarton, Ontario, and Shubenacadie Sam of Nova Scotia also saw their shadows.

"[Sam] saw his shadow and went back in,'' Nova Scotia provincial government spokeswoman Jacqueline Parker told Canwest news service. "It's six more weeks of winter."

Americans, Canadians and Britons need not be discouraged by the predictions, however.

An American newspaper's study suggests the celebrity groundhog may as well flip a coin as glance around for his shadow. In a study published this morning, the Atlanta Journal-Constitution found that Phil's predictions are accurate only 50% of the time, based on whether the temperatures in February or March are above or below the average.

According to a Canadian climatologist, Wiarton Willy is also only right half the time.

"It's no better than flipping a coin," David Phillips, senior meteorologist with Environment Canada, told the Globe and Mail newspaper.

According to the Punxsutawney Groundhog club, Groundhog day was brought to western Pennsylvania by German settlers. February 2 is often Candlemas Day, and is roughly midway through winter.

An old English folk song declares:

If Candlemas be fair and bright
Come, Winter, have another flight.
If Candlemas brings clouds and rain,
Go Winter and not come again.

*See also the film with Bill  Murray...:w00t: