UNDATED -- Beaches, swimming pools and oases of air conditioning are likely to be packed to overflowing Saturday as Californians seek relief from a torrid heat wave that has lasted nearly a week.

The sky-high temperatures that tested eletrical grids around the state for much of the week were expected to cool slightly Saturday and return to seasonal levels by Sunday.

More than 8,000 customers lost power when excessive energy demand caused a distribution station to fail in the North Hollywood area of Los Angeles on Friday, said city Department of Water and Power spokesman Joe Ramallo.

The utility registered a peak energy demand of 6,053 megawatts at 3:13 p.m., just 112 megawatts shy of the all-time record, Ramallo said.

"The system is under tremendous strain to meet the energy demand," he said.

The heat wave sent the mercury surging and broke records up and down the state: 103 degrees in San Jose, 105 in Escondido, 106 in Burbank and 108 in San Luis Obispo. The heat spread from the Salinas Valley to metropolitan Los Angeles and east across the inland deserts, with the usual Central Valley hotspots cooler than coastal areas.

In North Hollywood, Mission Uniform and Linen Services turned off lights to give the air conditioners more juice and handed out Gatorade and iced tea to drivers at its depot.

"We can't have them getting heatstroke on us," said manager Todd Martin.

Northeast winds blocked cooling sea breezes from penetrating a high-pressure system that kept its grip on the West after breaking or tying records for several days.

"It's increasing the misery," said National Weather Service spokesman Bill Hoffer.

Gov. Arnold Schwarzenegger directed the state Office of Emergency Services to be on standby for high temperatures through the weekend. The city of Los Angeles planned to keep senior centers and libraries open for extended hours Friday and Saturday, though the county planned to close 42 cooling centers over the weekend.

The National Weather Service issued a heat advisory for San Jose and other cities in Silicon Valley. Thirteen cooling centers were opened in San Jose, where Friday's high was 102.

About 20 miles south, the Morgan Hill Aquatics Center was packed Friday. On Thursday, more than 1,000 people used the pools and water slides, about twice the average for a weekday, said Pamela Bailey, 19, who works the front desk.

"This weekend is going to be crazy," Bailey said.

Enterprising people took advantage of the chance to offload spare air conditioners. In Los Angeles, Hans Sabal said he sold one for $300 within a day of posting an online ad.

"It was in storage for a year and it was gone in 24 hours," Sabal said.