Frank London’s Klezmer Brass All-Stars’ historical and spiritual forefathers are the legendary Inebriated Orchestra, a roving band of Jewish musicians who supposedly roamed the Eastern European countryside in the 19th century, playing an early version of what became modern-day klezmer.

The story goes that the orchestra raised hell everywhere they went, drinking and carousing through every town they stopped in, and Frank London and company may also have riled up forces of nature at the American Folk Festival on Saturday night. The sky opened up during their set at the Railroad Stage and a torrential downpour drenched the crowd and band alike.

While many of the audience members scurried for cover, about half of them stuck it out. And they were rewarded for their fortitude: The six-piece ensemble of world-class klezmer musicians played their guts out as the rain came down, picking up tempo and urgency as it poured harder and harder. The more free-spirited festival-goers embraced the inclement weather and danced barefoot in the soaking wet grass, hooting and hollering.

Eventually the band had to stop, lest someone get electrocuted. But they did what any good musician does when it starts to go down: They went with it. They stepped off stage into the audience and played without the aid of speakers or microphones for about 20 minutes. The crowd went just shy of totally nuts.

And then, like nothing even happened, the rain let up. It was just one of those you-had-to-be-there moments that’ll go down in folk festival history.