Harry and Meghan, George Clooney, Lady Gaga and Halle Berry are among the celebrities whose multi-million-dollar mansions are under threat by the severe storms battering California this week. 

The Pineapple Express, a weather system lingering over much of the Sunshine State, is causing chaos over several regions including the star-studded Beverly Hills, Malibu and Montecito neighborhoods. 

It's the second severe weather system to hammer the west coast over the past week, and it arrived just as Los Angeles welcomed celebrities for the Grammy Awards on Sunday night, prompting organizers to hastily assemble a tent over the red carpet. 

The National Weather Service has issued flash flood warnings covering several neighborhoods in California, and some residents have even been evacuated. 

During a dramatic operation in the early hours of Monday morning, LA firefighters rescued 16 people from nine properties in Studio City - the same neighborhood where George Clooney lives in his $2.2 million luxury pad. 

The Hollywood star recently transformed the mansion, which he originally bought from Fleetwood Mac singer Stevie Nicks in 1995, from a bachelor pad to a palatial estate fit for his wife Amal Clooney and their five-year-old twins Ella and Alexander. 

Many residents in the same neighborhood woke up Monday morning to find mud, rocks and debris strewn across the streets, while strong winds have blown bricks onto parked cars and pavements. 

Harry and Meghan's $14.65million Montecito mansion is also under a 'flood watch' warning for the next 28 hours, while their surrounding county, Santa Barbara, is predicted to be deluged with 5.1 inches of rain on Monday. 

The county's police department shared a video of brown water exploding out of Mission Creek across West Haley Street and De La Vina Street, turning roads into rivers on Sunday. 

Harry and Meghan live just a couple miles east with their two children Archie and Lilibet, in a mansion featuring two connected palm trees in the garden and a grand piano in the living room. 

Meanwhile, star-studded Malibu is being marred by torrential rain, and the city is currently under a coastal flood warning, with the NWS warning residents to stay out of the water due to 'dangerous surf conditions'. 

The luxury beachside city is home to the likes of Halle Berry, who has a $8.5 million mansion complete with an outdoor jacuzzi which she occasionally shows off on Instagram. 

The 57-year-old former Bond Girl's 5,000 square-foot pad sports four bedrooms each with a private balcony, and five bathrooms, while the actress' bedroom of choice features stunning sea views. 

Lady Gaga also owns a sprawling Malibu mansion - the same property where Bradley Cooper offered her the starring role of Ally in A Star Is Born, which she went on to win an Oscar for.  

The singer purchased the six-acre property in 2014 for a cool $24 million, with the palatial Mediterranean-style home overlooking Zuma Beach from a clifftop vantage point.

But apocalyptic scenes have broken out in the beachside city, with water and mud running down the streets in some areas despite ginormous sandbags being used to prevent landslides. 

Dramatic images show Malibu Pier being battered by strong waves on Sunday with the usual surfers and swimmers who swarm the shores nowhere to be seen. 

The National Weather Service has predicted the wider county of Los Angeles will be hammered with 6.37 inches of rain over Monday. 

It comes as more than half a million homes in California have been struck by power outages, and one man has reportedly died in Sacramento Valley after he was crushed by a toppled tree. 

At least 566, 502 households in the state suffered power cuts as of Monday morning, according to national tracker poweroutage.us. 

Downpours of up to 1 inch every hour could impact Los Angeles for a least 24 hours over Monday, forecasters have warned. 

The severe conditions prompted the National Weather Service's (NWS) Bay Area office to issue a rare hurricane-force wind warning for Big Sur and nearby areas.  Residents have been urged to 'protect life' and to stay home wherever possible. 

It comes as 82-year-old David Gomes died after he was struck by a large redwood tree in Yuba City, northern California, on Sunday night, per ABC10. 

Meanwhile in San Bernardino County, first responders rescued three people from a vehicle after it was deluged by surrounding floodwater during the night on Sunday. 

Dramatic footage shows a team using lifeboat rafts to approach the vehicle before helping the occupants escape to dry land. 

LA firefighters have also rescued 16 people from their homes on Lockridge Road, Studio City, after a debris flow caused 'significant damage' to nine properties.    

Department of Building and Safety is on scene evaluating the situation, the department said. 

The rain canceled the final round of the professional golf tournament at Pebble Beach in Northern California's Monterey County. Because heavy rain was forecast for Monday, the PGA Tour ended the event after only three days, naming Wyndham Clark the winner.

California Governor Gavin Newsom declared a state of emergency in eight counties with a combined population of more than 20 million people, and flash flood warnings were issued for parts of Los Angeles, Santa Barbara and San Luis Obispo counties.

'This has the potential to be a historic storm, severe winds, thunderstorms, and even brief tornadoes,' Los Angeles Mayor Karen Bass told a news conference.

Los Angeles experienced its 10th wettest day on record on Sunday - and the downtown region alone was deluged with 4.1 inches of rain.  

The San Francisco Bay Area and Los Angeles County were not only getting drenched but the storm was expected to stall or reverse course over some areas into Tuesday, creating severe risk of flooding and mudslides.