December Blows In on High Winds : Weather: Gusts of up to 40 m.p.h. cause power failures in the Valley and Pasadena. Nature’s bluster is expected to subside today.

November left town in a huff.

Continued strong, gusty winds rattled windows, blew sand and tumbleweeds and kept power repair crews busy Saturday, but it all brought smiles to the faces of windsurfers at Southern California beaches.

“This is perfect weather for windsurfing, when the gusts scoot right along the shore,” said an enthused Shawn Collins, a surfing forecaster with Surfline/Wavetrak, a wave conditions information service for surfers.

Gusts up to 30 knots out of the north-northwest billowed the colorful sails of windsurfers at beaches from south of Palos Verdes to Marina del Rey, said Lt. Sonny Vardeman, a Los Angeles County lifeguard.

But that was about the only thing good about November’s exit. Even regular water surfing was knocked down by the wind, which kept waves to only three to four feet despite 10-foot-high swells, Vardeman said.

About 5,000 Los Angeles customers were temporarily without power, and emergency crews were called in to repair electrical lines knocked down by strong gusts and falling tree branches, said Ed Freudenburg, spokesman for the Los Angeles Department of Water and Power.

The hardest hit area was the east San Fernando Valley, particularly the Sunland-Tujunga area.

Scattered power failures also were reported in areas of Mt. Washington and throughout the Harbor and West Los Angeles areas, Freudenburg said.

Southern California Edison Co. said 800 customers along the Colorado River at Lake Havasu were without power Saturday morning. That was the only significant power failure in the area served by the company.

Pasadena, hit by sporadic outages, brought in emergency repair crews beginning at 8 p.m. Friday and crews continued to work throughout Saturday, a spokeswoman said.

Both Southern California Edison and DWP officials attributed the relatively small number of power failures to aggressive tree-trimming programs. “Five or 10 years ago we would have had major, major problems from a windstorm like this,” Freudenburg said. “The tree-trimming program has really paid off.”

The gusty winds of up to 40 m.p.h. were expected to subside Saturday night and be markedly lighter today, said Steve Burback of WeatherData Inc., which supplies weather information to The Times.

A warming trend with diminishing winds is expected by Monday with temperatures climbing slightly above normal to the low- and mid-70s, according to WeatherData.

Firefighters on Saturday mopped up after a 140-acre brush fire that briefly threatened homes in Sylmar on Friday. The fire, believed to have been caused by an illegal campfire, caused little damage before it was contained.

In Van Nuys, city officials opened an old National Guard armory to the homeless because of the cold. The shelter, where 150 beds were available, was to remain open overnight.

It was the first time this season that the city’s shelter program had been activated, said spokeswoman Patricia Huff. No other city-sponsored shelters were scheduled to open Saturday night because temperatures were not expected to be cold enough elsewhere.

The National Weather Service must forecast temperatures of 40 or below, or 50 or below with a 50% chance of rain, before the city opens a shelter. Temperatures in the Valley were expected to dip to 38.

Times staff writer Mayerene Barker contributed to this story.