Wild southwest winds killed power Wednesday for thousands of O'ahu residents and sent pieces of roofs flying from homes islandwide as gusts of up to 69 mph moved ahead of a rain-packed cold front.

From Waimanalo to Waialua, about 30,000 customers lost electricity at some point during the day, a Hawaiian Electric Co. spokesman said. Most customers regained power in about two hours, but 300 Waimanalo residents were without power for most of the day after a tree fell on a utility pole near the Waimanalo Polo Field at about 6 a.m.

Most customers had power back as of 8:45 p.m., HECO spokesman Peter Rosegg said, but repair crews worked late into the night on small outages in Waimanalo and Mokule'ia.

Falling tree branches were a common cause of power outages, HECO spokeswoman Sharon Higa said. In Wahiawa, falling palm fronds were to blame for an outage that affected 2,000 customers.

"This will cause the circuit to trip the line," she said. "This is the equipment protecting itself. It is de-energizing that circuit. It's a safety feature."

The Honolulu Fire Department responded to 30 wind-related incidents Wednesday, none of them serious, said spokesman Capt. Kenison Tejada. Twenty-four of the calls were for roof damage.

Waiahole Elementary will be closed to students Thursday after the wind damaged the roof of a classroom building. The damage took place after students and staff had gone home for the day, and no injuries were reported.

Teachers and staff should report for work Thursday at Kahalu'u Elementary School.

The school is expected to be open on Friday.

Tejada said none of the problems was "catastrophic," but try telling that to Brandie Imai. The wind peeled roofing material into wads of black lumps that hung off her Keolu Drive home in Kailua.

"They said 90 percent of our roof is gone," Imai said.

It took all day for Imai to reach a roofer. She said the home had not developed any leaks and she didn't expect any problems — unless it rains.

"So I'm praying it doesn't rain," she said. But the rains did come Wednesday afternoon.

The wind's raw power could be seen and felt everywhere.

A plastic sign sailed through the air making a whooping sound as it barely missed an automobile in Kailua. On the highway a mangled pile of metal lay in a heap and car parts lay on the shoulder on the way to Waimanalo.

Trees were uprooted, fences were downed and dozens of ripe avocado splattered an intersection in Enchanted Lake.

Streets in Waimanalo, Kailua and Kane'ohe were littered with shingles, and people, including Phyllis DeCorte of Kailua and Marlene Lee of Kane'ohe, had to call the Fire Department to stop their roofs from shedding.

"We were afraid our neighbors were going to get hurt with the flying debris," DeCorte said.

It was the second time in three days that kona winds buffeted the state and prompted the National Weather Service to issue a wind advisory that was expected to last through 4 p.m. Thursday.

The gusts were strongest on the windward sides of mountain slopes as winds flowed west to east, up and over the mountains, gaining speed as they headed downslope.

Statewide, the strongest gust was 69 mph, recorded at the base of Kolekole Pass, the weather service said. Nearby Makua Ridge clocked in at 67 mph and across the island in Kailua, one gust reached 65 mph.

When the winds returned late Tuesday night they seemed to take particular aim at the city's traffic signals, damaging 50 to 60 of them Wednesday, said Ty Fukumitsu, acting chief of the city's Traffic Signals and Technology Division.

"We were repairing them all night long," he said. "It actually started Monday then died down and then came back overnight."

His entire staff of 12 spent most of Wednesday repairing the signals, which are 10 to 15 years old. Some were dangling, their plastic connections broken and some were tilted or angled away from their normal positions.

"They normally can withstand wind gusts of 40 mph but with the age of the lights, they tend to break," he said. "We have been able to keep up with the repairs, though."

Insurers reported more than 100 claims were filed since the winds roared into town Monday as homeowners reported damage to roofs, housing siding, fences and trees falling on residences and cars.

"We have seen a spike in claims," said Carolyn Fujioka, spokeswoman for State Farm Insurance, the largest homeowners insurer in the state. "It's not real unusual, but it's heavier than usual."

Island Insurance Cos. reported receiving 40 claims, while First Insurance Co. of Hawaii Ltd. said it had a dozen claims. Most came from Windward O'ahu.

John Schapperle, Island Insurance president, said the number of claims was expected because of the winds.

Reach Mike Gordon at mgordon@honoluluadvertiser.com and Eloise Aguiar at eaguiar@honoluluadvertiser.com.