California's blistering autumn heatwave has sent temperatures to an all-time record high of 45 Celsius in central Los Angeles, with many seeking refuge at the beach or in the shade.

The city hit the hot spot for a few minutes at about 12.15pm local time yesterday, breaking the old all-time record of 44 Celsius set on June 26 1990, said Stuart Seto, a weather specialist at the National Weather Service office in Oxnard. Temperature records for the area go back to 1877.

The historic mark was part of an onslaught of temperatures well over 100 degrees Fahrenheit (38 Celsius) in many cities ranging from Anaheim, home of Disneyland, to San Luis Obispo on the usually balmy Central Coast. Many records were set or tied.

Firefighters carried heavy hoses up hills to battle a small but persistent brush fire west of Los Angeles in Thousand Oaks, while other workers in less strenuous jobs also struggled through the day.

The giant Los Angeles Unified School District cancelled all outdoor activities, including sports competitions and practices.

Electrical demand was much higher than normal for this time of year but no problems or shortages were expected on the state grid, said Gregg Fishman, spokesman for the California Independent System Operator, which controls about 80% of the grid.

Demand was expected to reach 46,000 megawatts, compared to 38,300 megawatts a year earlier, he said.

Some people were able to seek relief at the beaches - though not in the hundreds of thousands who turned out over the weekend as the heatwave built.

The city of Los Angeles urged people to use Parks and Recreation facilities, OAP centres and libraries as cooling centres.

Umbrellas were the necessary accessory for many women venturing along sizzling pavements.

But the heat did not keep tourists from snapping pictures of the Walk of Fame stars on the Hollywood Boulevard pavement, but Don Macfarlane, 59, of Melbourne, Australia, said he would rather have been at the beach.

"I expected this part of the world to be fairly warm, but not quite this warm," he said.

It felt like an oven to Dilia Rosada, 24, a lawyer from the Dominican Republic who was in Los Angeles to meet her fiance's family.

"We thought it was going to be normal hot, but this is hotter than our country," she said.

The National Weather Service said the siege of dry heat was being caused by a ridge of high pressure over the West that was keeping the Pacific Ocean's normal moist and cool influence at bay.

Firefighters were on alert for wildfires, but there was little wind amid the onslaught of dry heat.

Red Flag warnings for fire danger were posted in some areas, but mostly due to the withering effect on vegetation alone rather than the dangerous combination of low humidity and offshore winds. Air movement remained breezy at best rather than forming the gusty Santa Ana winds linked to destructive wildfires.

The early autumn blast of intense heat follows an unusually cool summer that often found beaches covered in overcast and whipped by chilly winds.

The 113 degrees Fahrenheit registered in central Los Angeles would not be all that remarkable in the populous inland valleys and deserts of Southern California - the highest temperature recorded in Los Angeles County was 48 Celsius in the San Fernando Valley community of Woodland Hills on July 22, 2006 - but city centre highs are typically well below those areas.

Conditions were expected to remain hot today but not as extreme. Forecasters said the ridge would drift east and allow some cooling through the end of the week, with moist air flowing from the south east creating the possibility of showers and thunderstorms from tomorrow to Friday.

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