The second day of the seventh annual Pitchfork Music Festival began under gray skies in a thick, hot, and humid funk as publicists disseminated their emergency heat plan via email—“We have a CTA cooling bus station at the end of Flatstock [the poster exhibition] and another if needed on Ashland and Washington [and] we will give away one bottle of water to the first 6,000 people through the gate for both today and tomorrow”—though my favorite source for weather wisdom, Ginger Zee, said this morning that Saturday is supposed to be positively pleasant compared to the final day of the fest tomorrow.

The music on the main stages kicked off at 1 p.m. with Brooklyn vocalist and loop mistress Julianna Barwick, who electronically layered multi-part harmony vocals to create a one-woman female choir not unlike an army of Enya’s, though without the annoying New Age wispiness.

Unfortunately, the first half of Barwick’s gorgeous and lulling set had to compete at near-equal volume with Chrissy Murderbot and MC Zulu over on the second stage; the volume there only subsided midway through, by which point the sun came out, the temperature started to soar, and now it was the weather ruining the intended bliss.

Nevertheless, Barwick’s recent album “The Magic Place” has shot to the top of my list for further listening.

Rating for Julianna Barwick (when she could be heard without distractions): 7.1.

Next up, New York indie-rockers Woods veered between two poles throughout their set, one annoying and one sublime. In more conventional folk-rock mode, the group was sabotaged by band leader Jeremy Earl’s wispy, wimpy, and just plain weak vocals, to say nothing of the uninspired songwriting.

But for the other half of the set, when the band would lock into a trance-inducing groove (my colleague Greg Kot rightly invoked the mighty krautrock legends Can) and stretch out into noisy psychedelic jams that were everything that Animal Collective’s should have been last night but weren’t, the group was nothing short of brilliant. Which means I’m just gonna have to split the difference with my final grade.

Rating for Woods: 5.5.

Imagine a slightly sunnier, marginally less threatening Nick Cave fronting a groovy if unholy merger of the Bad Seeds and the Human League and you’re sort of closing in on what New York-based writer, musician, and publisher Wesley Eisold is doing with Cold Cave, which recently released the impressive “Cherish the Light Years” on Matador Records.

It’s always somewhat painful to see someone who so clearly thrives in the dark and would never be seen not wearing black struggling to create his vibe in the brutal summer sun, but Eisold did his best, and Cold Cave, like the good half of Woods, was a welcome surprise.

Rating for Cold Cave: 7.3.

As for the non-musical doings in Union Park today, I had my third (third!) encounter with a young woman hired by this year’s corporate beer vendor asking to survey me about my hops preferences and collect the data on her iPad (third time I’ve declined, too).

But, at the other end of the spectrum, the activists from Between Friends, Rape Victim Advocates, and several gay rights groups have been a much bigger presence today, handing out their hand fans and anti-violence literature as the crowds enter the front gate, as well as staffing their booth on the midway.

As good as some of the preceding acts were, the beats per minute stayed firmly in the “nod your head and bounce in place” range. But the tempo finally was upped to an inspiring head-banging frenzy with the 3:20 p.m. main-stage set by the L.A. hardcore punk duo No Age, and a sizable portion of the crowd responded in a spirited mosh pit.

On album, Randy Randall and Dean Allen Spunt can indulge in a fair amount of noise-rock experimentation. But like most smart punks, they know to stick to the basics on stage, dishing out adrenaline, adrenaline, and more adrenaline. Oh, and a rip-roaring cover of the Misfits’ “Hybrid Moments” to boot.

There really was just one word for what the band delivered: Ferocious. And, lord, was it needed at Pitchfork Day Two.

Rating for No Age: 8.8.

And then… back to the pointless, clichéd, mid-tempo electronic noodling. Was Manhattan’s arty electronic Gang Gang Dance as bad as Animal Collective in Grateful Dead mode Friday night? Almost. And at least Panda Bear and pals had a light show.

The set started out with about 10 minutes of grooveless beeps, squiggles, and synthesizer farts, and things only got marginally better when the drum machine kicked in. The utter lack of dynamic range, melodic ideas, rhythmic originality, or sonic diversity of any kind made the hourlong set easily seem six times as long.

Rating for Gang Gang Dance: 2.5.

My plan for Saturday had been to spare my intrepid colleague Althea Legaspi from having to leave the shade surrounding the second stage, but after Gang Gang Dance, I just wasn’t up for Destroyer. I didn’t have any expectations for this set being much better than the one at Pitchfork a few years back, especially after “Kaputt,” so I swapped with her for OFF! I desperately needed another dose of No Age-level energy.

Formed about two years ago, OFF! is an L.A. hardcore-punk supergroup comprising singer Keith Morris (Black Flag and the Circle Jerks), Dimitri Coats (Burning Brides), Mario Rubalcaba (Rocket From the Crypt), and the great Steven McDonald (Redd Kross). But the key word there is “hardcore,” and unlike pretty much every other supergroup in rock history, this one spends zero time resting on its members’ laurels.

In fact, OFF! spends zero time resting at all.

At past shows, Morris apparently has filled some of the time padding the group’s relatively short list of originals with a lot of stage patter. But that was kept to a minimum in Union Park as the band tore through one fierce but melodic burst of chaos after another. And what stage patter Morris did deliver was pretty funny.

“‘F*ck People’ is about, ‘F*ck people who text people on their cell phones while driving along, too important to show that they’re about to change lanes,’” Morris said, trying to explain exactly who he had been addressing in the pleasant little ditty the band had just played. “It’s about, ‘F*ck people who get in the 15 items or less line at the grocery store with 20 items.’ It’s not, ‘F*ck all you people,’ unless you’re one of those people. Then f*ck you!”

Ah, yes, this is exactly what Pitchfork 2011 needs! And Morris knew it, too.

“I really want to thank all of you for hanging out with us,” he said at the end of the set. “We’re kind of an odd flavor at the Pitchfork party.” Too true, too true.

Rating for OFF!: 9.4.

The problem with festival high points such as No Age and OFF! is that when the rest of the long, long day fails to measure up, the disappointment is all the more intense.

Some of the rest of Day 2 wasn’t bad. It just wasn’t that good.

With its mix of hard-hitting D.C. punk ala Jawbox and Fugazi and hints of R&B and hip-hop, Pitchfork the Webzine has credited the Dismemberment Plan, which broke up in 2003, as progenitors of the dance-punk explosion of more recent years. Hence anticipation was high in some corners for its reunion at the festival, but this was not one of those.

In the past, when it was pushing forward in a straightforward punk way, the group could be perfectly… O.K. But when it would break things down for a lazy beat-box interlude or experiment with more fonky grooves and snaky choruses, it generally lost the plot. The same held true as the band took the stage in Union Park, highlighting tunes from the recent reissue of “Emergency & I,” originally released in 1999, and the rest of its catalog.

Rating for the Dismemberment Plan: 4.1.

Though turntable artist DJ Shadow(Josh Davis) undeniably is brilliant at what he does—perhaps the best—booking him as the penultimate main-stage act was a big miscalculation. For one thing, his hypnotic breakbeats aren’t really an excitement-building, night-ending sound. For another, there just isn’t much for 18,000 people in a hot dirt field to watch.

Shadow tried to make up for this with the weirdest stage set-up yet seen at Pitchfork (and yes, it even was stranger than the Flaming Lips’ sideshow circus). Taking a big cue from Lady Gaga, he started his set hidden behind a giant egg, which only turned around to expose him midway through. The problem was, we were supposed to be entertained by video projections on this large white orb during the time when we couldn’t see him. But at 7:30 p.m., and for quite some time after, the sun still was too bright to fully enjoy whatever images he was showing, so all was for naught.

Rating for DJ Shadow: 5.3.

Finally, it was time for Fleet Foxes to close things out. Though I love their new album “Helplessness Blues,” and was blown away by how their beautiful, multi-part harmonies held the crowd in hushed awe when they played a midday set at the Pitchfork Music Festival a few years ago, I was dubious that they could pull off one of the three key headlining slots. The music is just too intimate.

Some people clearly agreed: There was a steady exodus out the gate and down Ashland Avenue shortly after the Seattle musicians began. But other devout fans had been camped out in front of the green stage since 1 p.m. specifically to claim a prime position for their heroes, and they were rewarded with perfectly spellbinding renditions of the group’s delicate but captivating and haunting yet uplifting tunes.

While current Pitchfork raves Bon Iver deserve nothing but scorn and derision for their modern take on Bread or America, Fleet Foxes are a welcome reminder that not all of the folk-rock of the ’70s should be forgotten. Still, they just weren’t as much fun as OFF!

Rating for Fleet Foxes: 8.5.

Meanwhile, on the second stage, here are the reviews from my colleague Althea Legaspi

Chrissy Murderbot and Sun Airways

G-Side, Destroyer, and the Radio Department

Twin Shadow and Zola Jesus