When Cherish the Ladies roll into town this week to play with the Augusta Symphony, the Grammy-award-winning group will be just shy of its 20th year on the road. Begun as a short concert series in New York City in the mid-’80s, they have since become one of the most successful Irish-American groups in Celtic music.

“It’s a long time coming,” said founder and flutist Joanie Madden, from a Maine hotel room that she claimed sat within spitting distance of the end of the world. “Years ago we’d be on the road and they’d say, ‘What are you doing on St. Patrick’s Day?’ ‘Oh, we’re booked,’ and they’d say, ‘Well, we’ll try next year.’ Now when we tell them we’re booked, they’d say, ‘Well, what are you doing in December?’ Celtic music: It’s not just for St. Patrick’s Day anymore.”

Madden’s wry humor punctuated by an infectious laugh is a key to understanding what makes these ladies stand out among Celtic musicians.

“The ambience that they set up with the audience is a very cheerful, happy mood. Their rhythms are just great. It just bodes well for a good fun evening and people leave on a high,” said Augusta Symphony Maestro Donald Portnoy. Put simply, they’re just fun.

And in Madden’s mind, it had better be. People spend their hard-earned money to see the group sing, play and stepdance.

“I take that very seriously, and I make sure that they have a laugh,” she said. “From when they arrive to getting out in the audience and shaking hands after the show.”

The group now does more than 150 cities a year, touring the globe with Madden on flute, whistle and vocals; Mary Coogan on guitar, banjo and mandolin; Heidi Talbot on lead vocals and bodhran; Mirella Murray on accordion and Roisin Dillon on fiddle. They bring with them two world-champion stepdancers, one of whom toured with Michael Flatley’s “Riverdance” extravaganza. In contrast with their beginnings, the group’s Christmas shows are now their most popular, bolstered by the Grammy-nominated CD that they recorded with what is probably the world’s most famous symphony.

“Talk about starting at the top,” Madden laughed. “We received a phone call from the Boston Pops.”

The legendary orchestra brought them in for one show, which turned into seven shows, an album and a CD, “The Celtic Album.” They lost the Grammy to celebrated cellist Yo-Yo Ma, an easy loss to take when work rolls in.

“The way we’re getting most of our work in the symphony world is the first violin from one symphony will call the principal violist in Atlanta and say, ‘Hey, you’ve gotta get these guys,’” Madden said. “I think it’s great to get them out of Rachmaninoff and Beethoven and get them playing 3,000-4,000-year-old jigs and reels. Eight of us and a 70-piece orchestra — if you can’t have a good time with us, there’s something wrong with you.”

Although the Irish musical tradition is famously strong, it was more often passed down from father to son. The Ladies were the first all-female traditional band, and established themselves on musicianship. Madden said it’s all natural.

“We’re all daughters of great musicians and we come from musical families. We’re just continuing to play the music that has been passed down to us.”

And they pass it along to sold-out audiences from America to Australia and everywhere in between in whom they find a nearly instinctive appreciation for Irish music, rich in storytelling and built on an oral tradition far removed from formal education.

“They can just connect to it. The tunes and melodies were written by people who didn’t know what key they were in. They wrote and played because it was beautiful,” Madden said.

And Americans adopted the music long ago, dipping it in Appalachia and pulling it out in the form of bluegrass, folk and country.

“Down South, people love folk music,” Madden laughed. One of their three shows is already sold out. Those audiences are what have kept Madden going for two decades.

“Sure I wanted to quit 100 times, but you get an e-mail from someone telling you that you changed their life, and it gives you the gas to go another two years,” she said. “And when you get tired, there’s another e-mail.”

Expect that the road will rise to meet her.