Mayall was to have concluded the show with a 6 p.m. performance.
"Look, it's passing over," Levi said. "People have spent a lot of money. People have come a long way."
Levi, who was standing in the middle of Public Square just after the announcement that the day's show had been halted, was among a scant few who remained of the 1,200 fans counted earlier by event staff in the main stage area.
The entire day wasn't lost. Those who attended the first half of the rain-shortened show had a good time.
Valarie Yvonne, 48, of Phoenixville, Pa., said she had driven an hour and a half to see the show, and she was impressed.
"I've been to other blues festivals in the area, but this one is a good one."
When the rain came, the umbrellas, raincoats and ponchos came out.
Pat Bailey, 51, of Funkstown, stood in an alcove near the stage during Maria Muldaur's set. The music was loud and clear, but all she could see was the crowd, which obscured the stage from her view.
"I can hear it," she said, adding that she had "already seen her," so that wasn't so bad.
Bailey said she thought many people had already been scared off by the rain.
"There's a lot of empty chairs," she said.
Sandy Hillman, 62, and a friend had traveled from Baltimore and were huddled under an umbrella.
"People that go to festivals are pretty hardy," Hillman said. "They're going to come back."
But minutes later organizers suspended the music as rain began falling steadily and thunder rumbled nearby. They asked the crowd to take shelter in the city parking deck on North Potomac Street.
Andy Butz, 40, who had come from Auburn, N.Y., for the festival, and a group of friends were looking for a bar to wait out the rain.
The wait turned out to be permanent, leaving hundreds of disappointed fans who would not get to see the final four acts scheduled.
While fans, volunteers and vendors expressed disappointment, many said they understood the safety concerns.
Jason Stottler, 31, was volunteering at the main gate Saturday and was bidding farewell to festival-goers.
"See you next year - or tomorrow," he told the exiting crowd.
The weekend blues event concludes with a concert in City Park today.
Stottler said the decision to stop the concert was probably difficult, but "somebody's got to make the call. ... I don't want to be out here, (with) 50 mile an hour winds, working the gate."
"I can see you got lightning in the air," said Bob Johnston, 47, of Sterling, Va. "It's just like a golf match. You can't have someone struck by lightning."
After learning the show had been stopped, Nicola Larsen, 46, of Shepherdstown, W.Va., frowned.
"We've been here all day, but we really came here to see the Blind Boys and Charlie Musselwhite," Larsen said. "They're not going to play them somewhere else?"
Her sister, Fiona Larsen, 28, when she heard about the cancellation, offered a lighthearted protest: "We won't melt."
Others who had retreated to the parking deck took the closing in stride.
Mae Brooks, 52, of Washington gathered with friends around the back of their minivan, sitting in fold-out chairs and sipping cool drinks.
"We're a little disappointed, but not dismayed," Brooks said.
While she wished the bands could have moved indoors, she said, "That's how the blues is. It rains sometimes."
Bad for business
Vinnie DiCola, 39, who owns Rocky's Pizza on Public Square, said he'd scheduled extra workers for the day, but the early end of the show made for disappointing business.
"I've already sent two people home. ... The weather definitely killed us," DiCola said.
About 4:30, the sun began peeking out from behind the clouds. DiCola looked up, and said, "I thought they could have kept going.
"This is definitely going to scare people next year if there's bad weather," he said.
Vel Hoffman had been running a funnel cake stand Saturday. Breaking down the stand to go home, she said, "I see blue sky. But that's a hard call to make.
"You do your best," Hoffman said. "We were doing well, but we'll come back."
The threatening weather may have kept some festival-goers from showing up.
"It was a very light crowd," said Ted Reeder, 42, of Hagerstown. "The weather definitely kept some people away. Last year it was jammed."
Hagerstown musician Pete Lancaster, who had performed earlier in the day, staged an impromptu concert in front of his store, Senior Notes, on North Potomac Street. Bruce Brong, of Boonsboro, played harmonica while Lancaster played guitar and sang.
Kathleen and David Hoza, of the Pittsburgh area, stopped to listen to the duo play after missing out on the headline acts that were rained out.
"Better than nothing," Kathleen Hoza said.