(photo: Tom Dellinger)

It was damn hot in the Bay Area this past weekend — so scorching that not even a semi-secluded spot high up in the mountains could escape the elevated temperatures. Those bristling conditions were what the attendees at the Sound Summit Music Festival — held in the historic Mountain Theater on the side of Mount Tamalpais — had to contend with on Saturday. Fortunately, a combination of great musical performances and an accommodating setup helped the event turn out to be a success, despite the sticky weather.

Headlined by alt-country act Wilco, the event featured five different bands, with music starting at 11am and lasting until dusk, at 7pm (there are no lights at the stone amphitheater). More power to those who lasted through the entire day — which started with sets from Matt Jaffe, The Stone Foxes, and Bill Frisell — but we didn’t arrive until just before Chicano-rockers Los Lobos took the stage at around 2:45 p.m.

The veteran East Los Angeles band delighted the crowd with a lengthy set filled with their back catalog of hits and a number of classy covers. The group’s take on Neil Young’s “Cinnamon Girl” was a particular hit with the audience, many of whom avoided the sunbaked stone steps of the amphitheater for the majority of the set, opting to find spots in the shade of the trees. By the time that Los Lobos closed down around 4:30pm, the heat had abated a little and the amphitheater began to fill up in earnest for Wilco.

Although Wilco vocalist and chief mastermind Jeff Tweedy has a soft, descending voice, his band wields an outsized presence. Long tagged with the alt-country label, Wilco is really more of a noise-rock band in a live setting, experimenting with lengthy, dissonant guitar interplay led by master musician Nels Cline. Even in a venue like the Mountain Theater — expansive, acoustically imperfect — the band had little trouble filling their environs with sound. No stage is too big for Wilco at this point in their career.

After opening with “Misunderstood” off their sophomore LP Being There, Tweedy and company carried through a trio of cuts from their just-released 10th album, Schmilco. Things started to pick up after the band played “Impossible Germany,” their gorgeous, exploratory track from 2007’s Sky Blue Sky, with much of the ensuing song selections coming from the band’s seminal 2001 release Yankee Hotel Foxtrot and its underrated follow-up, A Ghost is Born.

The real fireworks came for the encore, when Tweedy was joined by local legend Bob Weir as well as Frisell for a series of tracks from Wilco’s collaborative album with Billy Bragg. The whole gang finished the performance with a cover of The Beatle’s “Tomorrow Never Knows,” a fitting song to close out a memorable day.

It’s really hard to overstate the beauty of the venue, too — bands play to the backdrop vista of the Bay Area, where the Oakland and San Francisco skylines stretch out below. Sunsets are pretty damn divine there.

Still in its relative infancy, the Sound Summit Festival — which raises funds for Mount Tamalpais State Park — is a refreshingly low-key event. While there was a wait here and there at the food trucks and drink stands, the event felt neighborly and relaxed. Everyone seemed to mingle comfortably, and there was little of the put-upon feel that accompany many music festivals (although this was really a fest in name-only, as it’s more of multi-bill one-day concert). There were water stations available throughout the venue, and the host of volunteers who helped out at the event did their best to help anyone with questions.

It was a warm (emphasis on warm) community gathering where everyone from the block showed up to catch some great tunes. In short, an ideal Saturday.