Hearing good music outdoors often provides unexpected pleasures; a more relaxed atmosphere, communing with nature, a chance to chat with friends (quietly) without getting shushed too often.

Weather adds an unpredictable element to the mix (pardon the pun), as the audience for the closing North Carolina Symphony program at Cary’s Summerfest series, in the Koka Booth Amphitheatre, found out. With a threat of industrial-strength rain imminent, Summerfest artistic director William Henry Curry and the symphony folks decided to cut some time off their closing concert, while still providing the core of some good music, well played.

Italian pianist Antonio Pompa-Baldi was the guest soloist for one of classical music’s great concerti, Beethoven’s Piano Concerto No. 5 in E-flat, Op. 72, the “Emperor.” Pompa-Baldi, a silver medalist in the 2001 Van Cliburn International Piano Competition and distinguished professor of piano at the Cleveland Institute of Music, delivered the composition with grace, energy and considerable clarity, especially in the delicate music box-like figure at the end of the opening Allegro movement and throughout the exquisitely beautiful second Adagio un poco mosso movement.

One noticeable feature of this concerto is the frequent separation of soloist and orchestra, especially in the first movement, as if the piano is trading musical passages with all other instruments. Of course, the soloist and orchestra play together, too, but the movement often resembles more of a dialogue of two separate and distinct voices than a blend. Another interesting aspect to this concerto is that at times Beethoven seems to wear out the scales. This is especially true in the second movement and in the final Rondo: allegro movement. Up and down the scale goes the soloist, in either chords or arpeggios, in any number of configurations and combinations.

Saint-Saëns’ monumental Third Symphony in C-minor, Op. 78, is called the “Organ Symphony” because of the addition of an organ to the group of instruments. It is not an organ concerto, by any means. The organ part generally complements and augments the orchestral score, with few if any prominent solo passages or embellishments. What the organ does is add depth and sound to the composition.

The symphony was joined by Donna Jolly, organist at First Baptist Church, and two pianists, Robert Baldwin of Genesis Methodist Church in Cary and Janice McLaughlin, assistant symphony librarian, and all the forces came together to handle the demands of the score quite nicely. Because of the threat of bad weather, Curry cut out the first movement, choosing to begin with the Poco adagio movement in which the organ first joins.

Despite the possibility that the music might be lost in the open air, the symphony players offered quite a nice reading of the music, most notably in the second movement of the Beethoven concerto, which calls for delicacy and warmth and a velvety smooth accompaniment, especially in the strings, and in the Poco adagio movement of the Saint-Saëns symphony. Curry never seemed to hurry the players, letting the passages breathe and letting the pauses stand out.

And even with the heavy air, the players also provided crisp entrances and cutoffs, with sharp attacks in the forte passages as necessary. The several solo passages for winds were well played, especially the little sections by flute, clarinet, oboe and horn in the Saint-Saëns symphony’s closing movement.

But because the music was played in an outdoor amphitheater, there was amplification, and that tended to flatten out the depth of the sound, rendering it much more one-dimensional than one would hear in a concert hall. This was most noticeable in the Beethoven concerto. And because the amphitheater does not ordinarily accommodate a performance requiring anything that resembles a pipe organ, the organ part in the Saint-Saëns symphony was played on an electronic instrument that, alas, did not deliver the full-throated sound one usually associates with the rich conclusion to the music. This was no fault of the organist. Ms. Jolly could be heard throughout, as could the piano four-hands passages, but that wonderful “oomph” that can be so dazzling — one of the grandest conclusions to any symphony in the repertoire — came up a bit short.

Nonetheless, an enjoyable concert on a sprinkly night, played against the backdrop of a lake and in front of a sea of umbrellas. With an eye toward the storm front, Curry cut out the opening selection (movements from Handel’s Music for the Royal Fireworks) but, as the rain held off, he offered an appropriate encore, Strauss’ “Thunder and Lightning Polka,” to bring the evening to an end.  No thunder and lightning from the heavens, but considerable electric energy from the musicians.