LOS ANGELES (AP) – Parts of Southern California sweltered in triple-digit temperatures on Monday as a heat wave stretched into the seventh day and contributed to power outages that left thousands with without air conditioning.

Temperatures soared in the San Fernando Valley with Woodland Hills reporting 102 degrees and Van Nuys at 99, according to the National Weather Service. Downtown Los Angeles also was expected to see temperatures climb above 100.

Southern California Edison said 20,000 customers in Los Angeles, Orange, Ventura, Riverside and San Bernardino counties had no electricity, spokesman Steve Conroy said.

About 3,500 more customers in scattered parts of Los Angeles also were without power, Los Angeles Department of Water and Power spokeswoman MaryAnne Piersen said.

“Probably more than 90 percent of them are due to stress on the system due to the heat,” she said. “Different pieces of equipment get fatigued and blow out, so they have to be replaced.”

Lightning strikes on grid equipment due to scattered desert thunderstorms also were adding to the strain.

The California Independent System Operator, which oversees the state’s power grid, said no major shortages were expected.

But it was urging customers to conserve electricity by setting air conditioning thermostats higher and waiting to use major appliances until after dark.

Relief was in sight with cooler temperatures forecast over the next several days.

“Everyone will see a drop of eight to 11 degrees on Tuesday,” said Stuart Seto of the National Weather Service. “By Thursday, things will be getting back to normal.”

AP-ES-09-03-07 1836EDT