Nothing makes a fan of Celtic music feel more at home at a concert than a little rain. But when the drizzle turned into a downpour at the Montgomery County Fairgrounds Saturday afternoon, even the hardiest souls attending the 23rd annual Washington Irish Festival ran for cover.

Fortunately, there was no shortage of shelter from the storm. Stages were set up in tents and barns throughout the fairgrounds, offering a virtually nonstop soundtrack of Celtic music. Much of it was firmly rooted in traditional styles, and as always the event's programmers were careful to showcase the talent of veteran musicians and relative newcomers alike.

Among the Irish groups performing at the festival for the first time Saturday were Lunasa and Danu. Both ensembles are composed of young but seasoned musicians well versed in traditional styles.

At its most exhilarating, Lunasa's performance featured revolving melodies played on flute, fiddle and pipes soaring over sharply percussive rhythms. The absence of a bodhran, the hand drum often used by Irish bands, was hardly noticed, since bassist Trevor Hutchinson and guitarist Donagh Hennessey charged the reels with a driving, propulsive momentum. When the mood and the meter shifted with the introduction of a lovely Celtic air or an engaging slip jig, the music frequently turned soulful and resonant, warmed by the sounds of Kevin Crawford's flute, Sean Smyth's fiddle and Cillian Vallely's uilleann pipes.

Afterward, at a nearby cattle barn converted to a concert hall, Danu delighted a packed house with a collection of traditional instrumentals punctuated by ballads beautifully performed by sean nos (old-style) singer Ciaran O Gealbhain. The septet's reels and jigs kept a dozen small children whirling about in front of the stage, as if auditioning for a "Romper Room" version of "Riverdance."

Yet for all the gaiety it produced, the ensemble's musicianship was as precise as it was spirited. A textured weave of instrumental colors produced by bouzouki, fiddle, bodhran, flute, guitar and accordion enhanced the arrangements, and O Gealbhain's affecting tenor colored his ancient tales of love, mayhem and comeuppance. Small wonder that kids and adults alike were sad to see the show end.