LOS ANGELES (CNS) - A blast of extreme heat will grip much of Los Angeles County Wednesday, with temperatures reaching as high as 108 degrees and oppressive humidity expected a day after thunderstorms, lightning and high surf battered parts of the Southland and damaged beachfront homes.

An extreme heat warning will take effect at 8 a.m. Wednesday and continue until 8 p.m. Thursday for much of Los Angeles County, with the National Weather Service forecasting highs from the mid-80s and lower 90s at the beaches to as high as 108 degrees in interior areas.

Forecasters said high pressure will peak over the region Wednesday, while lingering moisture from former Hurricane Marie will combine with the heat to make conditions especially uncomfortable.

"Unfortunately with these temperatures, surface dew points are expected to be in the mid 60s to mid 70s (thanks to Marie), making conditions VERY oppressive," according to the NWS.

The weather service said there will be widespread "major heat risk" and localized pockets of "extreme heat risk" Wednesday and Thursday. Overnight temperatures will provide limited relief, falling only into the mid- 60s to mid-70s through Thursday night.

Temperatures are expected to drop several degrees Thursday before cooling another 4 to 8 degrees Friday, which forecasters said should greatly reduce the heat risk.

The heat follows another round of rain and thunderstorms Tuesday as moisture from Marie moved through the region. Rain fell in areas including Burbank, Arcadia, Glendora, LAX and Manhattan Beach, while thunderstorms produced lightning across portions of Los Angeles County.

Los Angeles County lifeguards temporarily closed beaches from Cabrillo Beach to Zuma Beach Tuesday morning because of lightning.

The storm also produced high surf that damaged beachfront properties in Long Beach, Dana Point and Malibu.

About 20 homes were evacuated along Seaside Walk in Long Beach Monday night because of a compromised seawall and damage to the boardwalk, according to the Long Beach Fire Department.

In south Orange County's Dana Point, about a dozen high-priced homes were red-tagged as uninhabitable following damage from high waves.

In Malibu, pounding surf undermined the driveway of a beachfront home reportedly owned by actor Nicolas Cage Tuesday and caused a gas main rupture. Los Angeles County Fire Department crews responded at about 5:45 a.m. to the 31600 block of Sea Level Drive East, near Point Lechuza. The home was unoccupied.

Although the south swell from Marie was subsiding, the NWS said coastal impacts could continue Wednesday and Thursday around evening high tides.

"Expect continued beach erosion, flooded sandy beach areas, bike paths, and parking lots, as well as low-lying roads," the NWS said.

A beach hazards statement will remain in effect through Thursday evening for portions of the Los Angeles County coast, with dangerous rip currents and some lingering southerly swell expected.

Forecasters said there is also a low chance of thunderstorms at beaches Wednesday.

The Los Angeles County Department of Public Health extended an ocean water quality rain advisory for all county beaches until at least noon Thursday because of rainfall. Beach users were advised to avoid all water contact, particularly near storm drains, creeks and rivers, where runoff can carry elevated levels of bacteria and other contaminants.

Officials had already urged inexperienced swimmers to stay out of the water because of dangerous rip currents.

Los Angeles County health officials also urged residents to stay hydrated, avoid outdoor activity during the hottest hours of the day and check on people at greater risk of heat-related illness, including older adults, young children, outdoor workers and people with chronic medical conditions.

"Heat causes more deaths in the U.S. annually than floods, storms, and lightning combined," Los Angeles County Health Officer Dr. Muntu Davis said in a statement. "Those most likely to get ill during the heat include older adults, young children, outdoor workers, athletes, and individuals with chronic medical conditions."

Residents without air conditioning were encouraged to use cooling centers, libraries, shopping malls and other air-conditioned locations. Information about cooling centers is available by calling 211 or at ready.lacounty.gov/heat/.

Gary and Shannon

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