BANGOR — Heavy snow fell across the northern half of Maine in the state’s first major snowstorm of the season today, knocking out power for thousands of homes and businesses, closing scores of schools, and causing treacherous travel conditions.

Nearly a foot of snow had fallen in many places by this afternoon, with the National Weather Service calling for some locations to get 20 inches by the time the snow stopped in the overnight hours.

More than 2,000 homes and businesses were without power due to heavy snow, and conditions forced several roads to be closed. Route 9, the busy east-west highway from Calais to Bangor, was shut down for several hours after a number of tractor-trailer trucks slid off or blocked the road, but no injuries were reported.

A late-fall storm with more than a foot isn’t unusual in northern Maine, said Joe Hewitt, a National Weather Service meteorologist in Caribou.

“Up here, by late November winter’s arrived,” Hewitt said.

The storm caused businesses and courts to shut down for the day, while schools and universities, including the University of Maine in Orono, canceled classes.

The snowstorm was welcomed by outdoors enthusiasts, particularly after last winter’s warm temperatures and relatively light snowfall.

Snowmobile clubs are heartened that recent storms coming into Maine have come from the east, which can be big snowmakers in the winter, said Bob Meyers, executive director of the Maine Snowmobile Association. About 100,000 people ride snowmobiles each year in Maine, which has 14,500 miles of trails.

“This storm can be only good news,” Meyers said. “It’s got everybody jazzed up.”