The War on Drugs and Nathaniel Rateliff & the Night Sweats will headline the XPoNential Music Festival when the weekend-long gathering presented by University of Pennsylvania radio station WXPN-FM (88.5) returns to the Delaware River waterfront in Camden in September.

The Adam Granduciel-led The War on Drugs, the Grammy-winning Philadelphia band who are currently in the midst of a European tour, will be back in support of their 2021 I Don’t Live Here Anymore to headline a terrific triple lineup on the first night of the fest on Friday, Sept. 16.

The opening acts are legendary punk rock poet Patti Smith, who grew up in the Germantown section of Philadelphia and in Glassboro in South Jersey, and Geese, the buzzed-about New York upstarts whose 2022 self-titled debut has earned comparisons to the Strokes and Television.

The second night of the fest is topped by Rateliff & the Night Sweats, the Denver, Colo., band who became a star attraction among public radio audiences with their 2015 self-titled album. Also on the Saturday night bill is New Orleans octet the Revivalists and rising local brass band Snacktime Philly.

Both of those shows are taking place at the indoor-outdoor Waterfront Music Pavilion (WMP), the Camden amphitheater formerly known as the BB&T Pavilion that’s currently in search of a new naming rights sponsor.

» READ MORE: Review: The War on Drugs, triumphant in the first of two hometown shows at The Met

And besides those six bands playing the WMP, the XPoNential fest will include more than 20 acts playing outside on two stages next door at Wiggins Park on Friday in the early evening and all day Saturday and Sunday.

The bill for the more intimate portion of the fest is topped by indie rock veteran Jenny Lewis, blues legend Taj Mahal, and Canadian songwriter Kathleen Edwards.

The rest of lineup is varied and deep. Standouts including banjo-playing songwriter Valerie June, honky-tonk heroes Sarah Shook & the Disarmers, Gulf Coast soul band Suffers, Los Angeles trio Lo Moon, upstate New York sibling act Felice Brothers, indie rocker Bartees Strange, Americana songwriter Buffalo Nichols, Chicago Latinx psychedelic band Dos Santos, and Belgian Egyptian singer Tamino.

The Black Opry Revue, the traveling group of Black country and folk artists with a rotating cast, are on the Wiggins bill, as are Philadelphia bands Cosmic Guilt, Catbite, Omar’s Hat, The Tisburys, Highnoon, and Chestnut Grove. Which days which artists are playing has yet to be announced. More Wiggins Park acts will be announced in the coming weeks.

» READ MORE: Black Opry Revue showcases Black country and folk singers

Last year, XPoNential was staged in September for the first time after previously being a longtime late July fixture. The move was not COVID-19 related; it had been planned before the pandemic in hopes of avoiding heat and thunderstorms in the height of summer.

Many of this year’s acts are making return trips to XPoNential. The War On Drugs first played in 2008, and then again in 2012 and 2018. Edwards played the fest in 2003, 2012, and 2019 and Smith, who is billed this year as Patti Smith & Her Band, appeared in 2005. Rateliff was scheduled to be a headliner at the 2020 fest, which was canceled due to COVID-19.

Tickets go on sale at 10 a.m. on April 22 at