Even if it’s 100 degrees, sweaters or jackets should be required at any I’m With Her concert, because Sara Watkins, Sarah Jarosz and Aoife O’Donovan will send shivers up and down concertgoers’ spines.

Singing in harmony so close it sounds like one voice, Watkins, Jarosz and O’Donovan occupy a semicircle of microphones ringed by instruments – electric and acoustic guitar, fiddle and ukulele for Watkins; mandolin, electric guitar, bass mandolin and banjo for Jarosz; and electric and acoustic guitar for O’Donovan – allowing them to effortlessly switch up their sound, as they did early and often during their mind-blowing show in a sold-out Memorial Hall OTR in Cincinnati.

Their vocal and instrumental virtuosity notwithstanding, the women of I’m With Her are also seasoned composers. “Overland” is a 2018 travel song that sounds like it could have been written in 1918 – with Watkins and O’Donovan on guitar and Jarosz on banjo, the singers sung of literally leaving home while figuratively going home during one of the concert’s many near-religious moments.

“Brother, I’ve made up my mind/got a ticket on the Union Line,” they sung, their voices rising with each word, “I know we’ll meet again on the other side.”

Take any superlative modified by any adverb, and you still couldn’t adequately describe the quality of this 90-minute performance. But of all the people in the house, the musicians, who looked and smiled at one another in exuberant friendship from the first note to the last, may have enjoyed it most of all.

The trio sauntered on stage without introduction just after 9 p.m. and lit in to the title track from their terrific full-length debut, See You Around.

From there, and from left to right, Watkins, Jarosz and O’Donovan alternated leads, supported one another on harmonies and played in as many combinations as their eclectic musicianship would allow – from bass mandolin and three voices on Adele’s funky “Send My Love (To You New Lover)” to electric guitar, banjo and acoustic guitar on their own Joni Mitchell-inspired “I 89” to two electric guitars and violin on the sultry original “Ryland (Under the Apple Tree).”

Eschewing their solo material – save for O’Donovan’s “Hornets,” which featured her bandmates on the studio version – I’m With Her instead played nearly every original and cover song they’ve officially released on singles, their 2017 EP and the new LP, which dripped out piecemeal throughout the show rather than in a sequential chunk.

Retaining pronouns and playing folkies, they sang of Jim Croce’s “hard-lovin’ Georgia girl” on “Walkin’ Back to Georgia;” channeling the esoteric bluegrass of the Punch Brothers, they sang of taking chances for romance on “Game to Lose;” and waxing optimistic, they exuded joy on Tom Brosseau’s “Today is a Bright New Day.”

For the four-song encore – which came entirely too soon – the band unplugged and moved up front to gather around a single mic at the lip of the stage.

The one-two punch of the original “Wild One” – “do not cross over, don’t get yourself undone,” they gently advised – and Bill Monroe’s raucous “Lord Lead Me On,” proved without a doubt that secular and spiritual belong back to back in the I’m With Her songbook.

And lest their fans think they’re singers first and instrumentalists second, Watkins on fiddle, Jarosz on mandolin and O’Donovan on acoustic guitar played a modern square dance on the wordless original “Waitsfield.” And lest their fans think they’re instrumentalists first and singers second, they stomped and clapped their way through a jaw-dropping, a cappella take of Nina Simone’s “Be My Husband.”

The pin-drop quiet audience exploded in applause when the women stomped their last stomp and clapped their last clap and walked off stage for the final time.