Homes were left without power, downed trees damaged dozens of cars and school was cancelled for thousands of kids as a blast of record snow slammed many parts of southern Alberta yesterday.

Blustery winds and a record 7 cm of snow for this day in history took down trees and electrical and telephone lines, causing power outages for more than 7,000 homes and damaging cars and buildings around Calgary, say city fire and Enmax officials.

The wintry blast topped the previous snowfall mark of 5.1 cm for May 24, set in 1911, with communities on the city's northwestern edge among the hardest hit.

And such meteorological mayhem is hardly unheard of this time of year, said Dan Kulak of Environment Canada, who noted May weather in the Calgary region can change at a moment's notice.

"In a couple of hours of driving you can go from tornado weather to snow tires," he said.

Yesterday's snow felled more than 12 power lines and wrecked yards around the city, including some where trees punched holes in car windshields, said Enmax spokesman Peter Hunt.

"It was really heavy, wet snow bringing down parts of trees or whole trees down on power lines that was the cause of all the havoc in the morning," said Hunt.

"We started getting calls at 4:50 a.m. and had almost all the power back on by 9:30 a.m., but the timing of the snow couldn't have been more disruptive because it was just before the rush hour."

A handful of customers were still without electricity about 2 p.m., but crews were working to restore full power, added Hunt.

Despite answering 54 calls in the morning, city fire crews reported no injuries, said spokesman Peter Budai.

"Firefighters were cordoning off areas for many of the major incidents such as trees falling onto houses and roadways being blocked off by some good-sized trees," he said.

Gordon Kennedy said the scene in Carstairs, north of Calgary, was worse than what was reported in the city.

"It looks like a hurricane went through," said Kennedy.

"Big trees that have been here forever are down, and they came down on cars, houses and buildings."

Power outages also hit Red Deer, where schools were forced to close.