Forecasters predict Los Angeles could have its biggest storm for two years from Friday and potentially through the weekend, when the movie industry's finest come together for the climax of the annual awards season.
Three movies -- harrowing historical drama "12 Years a Slave," 3D space thriller "Gravity" and 1970s crime caper "American Hustle" -- are leading a packed field for the top prizes.
On the acting front, Cate Blanchett is the hot favorite for her turn in Woody Allen's "Blue Jasmine," while Matthew McConaughey is widely tipped to strike Oscars gold for his portrayal of homophobic AIDS activist Ron Woodroof in "Dallas Buyers Club."
Jared Leto's role as Woodroof's unlikely transgender business partner has put him ahead of the field for best supporting actor, and Lupita Nyong'o could take home a statuette for her big-screen debut in "12 Years a Slave."
But all bets are off for the big prize of the night, the best picture Oscar, which will be handed out at the end of the 86th Academy Awards ceremony hosted by US talk show host Ellen DeGeneres.
"There's going to be genuine suspense this year when that final envelope is opened," awards consultant Tony Angellotti told the Los Angeles Times.
The 6,000 or so voting members of the Academy of Motion Picture Arts and Sciences cast their ballots over 12 days starting on Valentine's Day and ending on Tuesday.
But the best picture race is so close that the winner could come down to only a few votes, under the Academy's preferential voting system. Under the rules, voters rank all nine nominated films.
They are: "American Hustle," "Captain Phillips," "Dallas Buyers Club," "Gravity," "Her," "Nebraska," "Philomena," "12 Years A Slave" and Martin Scorsese's "The Wolf of Wall Street."
Those with the least first-place votes are dropped, and their votes given to the next highest-ranked nominees. This continues until one movie has 50 percent plus one vote.
It has been a long awards season -- extended by the Sochi Winter Olympics, which bumped the Oscars from February into March.
And it has also been among the most grueling, partly due to the bumper crop of films vying for glory.
Topping nominations are "American Hustle" and Mexican director Alfonso Cuaron's "Gravity," with 10 nods apiece, followed by "12 Years a Slave," a true story of a black man sold into slavery, with nine.
Cuaron is the frontrunner for the best director prize, and his star Sandra Bullock earned high praise for her work in the spectacular space drama, prompting some to suggest she could cause an upset in the best actress race.
But Australia's Blanchett remains the firm favorite in that category, despite a strong field also containing Meryl Streep ("August: Osage County"), Judi Dench ("Philomena") and Amy Adams ("American Hustle").
The star-studded Oscars broadcast will feature performances by Irish rockers U2, playing their nominated song from "Mandela: Long Walk To Freedom," and a first Oscars turn by veteran Bette Midler.
Sunday night's show will be preceded by the usual fashion extravaganza on the red carpet, as Tinseltown's finest parade along Hollywood Boulevard and into the Dolby Theatre.
Organizers hope rain doesn't affect the parade; they hastily rescheduled the carpet roll-out to avoid forecast rain earlier in the week, and said Thursday they were reviewing some camera positions, partly due to the weather.
The storm clouds come as a relief to many locals, as California has been suffering its worst drought for a century over the last few months, threatening farmers and cattle ranchers.
But for organizers of Tinseltown's biggest night, it is probably one headache they could do without.