‘Erin’ Go Bragh at Box Office?

Julia Roberts’ new movie “Erin Brockovich” should turn its St. Patrick’s Day competition green with envy.

“Erin Brockovich” The biopic’s well-attended sneaks Saturday helped jump-start favorable word of mouth about the R-rated drama about a real-life law-firm secretary (Roberts) who takes on a giant corporation over the poisoning of a California community’s water supply.

“Erin Brockovich,” opening at 2,845 theaters, is well-positioned to do blockbuster business.

“We’ve got a monster coming,” predicts an insider at a competing studio. “I feel like the guys at the National Weather Service who track the hurricanes. Hurricane Erin is coming!”

How big a hurricane does he anticipate? Given that the film is being cited by 27 percent of filmgoers as their must-see flick of the weekend, the insider said he’s guessing “Erin Brockovich” could do “$30 million plus.” (The standing record for a March opening was set in 1997 when Jim Carrey’s “Liar, Liar” opened with $31.4 million.)

“There’s a lot of pent-up demand for it,” notes another distributor about “Erin Brockovich.” “That older female audience, in particular, has had nothing to go see.

“Although the movie’s not limited to females. Males will like it, too. It’s got money written all over it. It’s what you want to have from a Julia Roberts movie. Men, women, everybody will go.”

After “Erin Brockovich,” everything else is looking like also-rans, including last weekend’s No. 1: “Mission to Mars.” Another insider predicted it wouldn’t do much more than $13 million this weekend — although that likely would be more than enough to place second.

According to Hollywood sources, the new suspense thriller “Final Destination” will battle family film “My Dog Skip” for third place, with a possible $5 mil to $6 mil apiece. And Roman Polanski’s “The Ninth Gate” could nab the fifth slot with a possible $4 million.

Expected to fill lower rungs on this weekend’s chart are four returning films: “The Whole Nine Yards,” “American Beauty,” “Drowning Mona” and “The Next Best Thing.”