Bjork headlines at the Coachella Valley Music & Arts Festival on Friday, April 27, 2007.[AP]

With a lineup of performers as hot as the triple-digit weather, tens of thousands of music fans descended on the California desert Saturday for the second of three days of performances by the Red Hot Chili Peppers, Arcade Fire, Bjork, Peaches and scores of others.

The bikini-clad women and bare-chested men who arrived early for the festival's second day battled the intense heat by guzzling water while they milled around the Empire Polo Fields, checking out the towering steel sculptures that dotted the grounds.

Hours before, during the festival's first day, they had swayed happily to stellar performances by Bjork, music's eclectic chanteuse, and raunchy rapper Peaches. On tap for Saturday were, among others, the Red Hot Chili Peppers and Arcade Fire.

"I went to Coachella three years ago. It's the pit of hell, but every year there's something stunning," said 18-year-old musician Jordan Deherrera, who was wearing a trucker's hat over a bandanna.

More than 50,000 concertgoers braved the scorching temperatures, traffic jams and long entrance lines to see 37 bands and DJs on Friday. There were 25 arrests, mostly for alcohol, drugs or unruly conduct, Indio Police Department spokesman Ben Guitron said.

Bjork kicked off a world tour with a colorful, headlining performance Friday night on the main stage.

Joined by an all-female brass band dressed in Day-Glo green, orange and blue, the Icelandic singer wore a multicolored headdress with floor-length cape. She soon threw it off, revealing a black and white bone bodice with green and orange hula skirt that rivaled the attention-grabbing swan outfit she wore to the 2001 Academy Awards.

Swaying, barefoot and skipping in the night breeze, facing a field of screaming fans, she launched into the bombastic "Earth Intruders," the first single from her upcoming album, "Volta."

An energetic set of old and new songs followed, from operatic '90s hit "Army of Me" to the Timbaland-produced new tune "Innocence" and politically charged "Declare Independence."

"Raise your flag!" she sang with an ironic growl, while her chorus of brass players chimed in "higher, higher!," shaking flags attached to their outfits.

"She's amazing," said singer-songwriter Rufus Wainwright, who played earlier that night. "As usual, I'm jealous of Bjork. I have only one French horn player, she has many more."

Bjork's rallying cry reflected the socially conscious sentiment of other performers at the festival, where '90s politicos Rage Against the Machine will reunite on Sunday.

"There's still a war going on, no matter that there's a fest," rocker-rapper Peaches (real name Merrill Nisker) told The Associated Press before her set, adding that she didn't think enough women played the event.

"It's still pretty white, guitar rock," she said.

But to sweaty, smiling 19-year-old friends Kristina Babayans and Jenna Munoz, Peaches was a top draw.

"She's rad and she's bold," said Babayans, squished to the front of the crowd.

Appropriately, porn star Ron Jeremy introduced the black leather catsuit-clad Canadian musician, who ran onstage wearing a gold mask and carrying a light saber.

Singing the opening track of her new newest album, "Impeach My Bush," Peaches yelled out "impeach Bush, impeach Bush!" to roars from the packed audience.

Across the fairgrounds, at the smaller Gobi tent, British singer Amy Winehouse brought on a more sedate dash of steamy sassiness.

Backed by eight-piece funk band the Dap-Kings, the bouffant-haired Winehouse crooned and joked, showing off her new engagement ring and hoisting up her tank top in the heat.

"Between the shoes and the hair, I'm not that big. I just met Danny DeVito. I'm his size," she told the crowd, which spilled past the tent's confines.

Other celebrity fans in attendance included Kelly Osbourne and Cameron Diaz.

Additional highlights included L.A. indie rock troupe the Silversun Pickups, rapper Busdriver and newly reunited Scottish band the Jesus and Mary Chain, who played a flawless set of '90s hits, including the hypnotic "Just Like Honey" with guest Scarlett Johansson.

Buzz artists at the festival include pop-reggae newcomer Lily Allen and Brazil's CSS.