More than 9,000 HECO customers lost power at one time or another between 4:34 p.m. yesterday and 8:45 a.m. today, when power was restored to the last darkened home.

But the strong winds — caused by a high-pressure system north of the state — are expected to continue through Thursday and the National Weather Service maintained a wind advisory today for all areas exposed to northeast tradewinds.

Sustained winds of 30 mph were forecast as well as gusts of up to 45 mph.

Leeward locations were expected to feel the fiercest gusts due to the way winds accelerate over the mountains, said lead forecaster Tim Craig.

"The winds get accelerated downslope," he said today.

HECO was busy with six different power failures yesterday and today, all of them wind-related, said spokesman Peter Rosegg.

"It was spread all over," he said. "From Nanakuli to downtown. It was a busy night last night, no denying."

From 4:34 to 5:03 p.m. yesterday, about 1,500 customers were without power in Mo'ili'ili.

From 4:40 to 5:03 p.m. yesterday, 20 customers on Sand Island lost power.

From 7:55 to 9:50 p.m. yesterday, 2,000 customers in upper Makiki lost power.

From 8:21 to 10:38 p.m. yesterday, about 2,400 customers in the Kalihi-Fort Shafter-Mapunapuna area were without power.

From 10:53 to 11:45 p.m. yesterday, about 2,300 customers in Nu'uanu lost power.

And from 5 to 8:45 a.m. today, 800 customers in Manoa were without power.

Blame the outages on the boughs.

"It was an unusually windy day and after a relatively long period without too much wind, it shook the trees that hadn't been shaken in a while," Rosegg said. "So it created some problems."

In addition to HECO crews, police and fire personnel responded to many calls about arcing electrical wires and other wind-related problems. A downed tree blocked both lanes of O'ahu Avenue in Manoa at 9:39 p.m.

The strong northeast winds also prompted the weather service to issue a high-surf advisory for all islands, with waves expected to reach 8 feet along east shores. A small-craft advisory was in effect.