The Spokane Symphony’s Labor Day Weekend concerts may be annual affairs, but the unpredictable outdoor settings keep the musicians on their toes year after year.

Moving the 70-piece orchestra, the chairs and music stands they require and the vinyl shell under which the symphony performs to the parks is all part of a process that begins the week before the show.

General Manager Dan Cotter, who also plays second clarinet in the symphony, said production manager Chuck Karschney is the mastermind behind the move.

“We have one truck and he packs it,” Cotter said. “It looks like Jenga when he gets done where everything is perfectly placed to fit it all in.”

The orchestra is using a newer shell after its old one died a truly fiery death, the result of teens setting fire to a stolen car they crashed into a Spokane Parks Department warehouse, where the shell and its steel frame were being stored, in an attempt to destroy the evidence of their joyride.

But the new shell is actually easier to set up, taking a smaller crew a day to do the work, instead of taking a larger crews two days to do the job.

Temperature can also play a big part in the success of the Labor Day weekend concerts.

As part of their union contract, the musicians have a temperature window of 65 to 90 degrees. Too hot or too cold, and the instruments could be in trouble.

“(The clarinet) can crack if you’re outside playing in the cold because you’re putting warm, moist air into the center of the clarinet so it’s expanding,” Cotter said. “Then the outside is cold and contracting and dry and it creates opposing forces that can crack your instrument.”

Two years ago, cold temperatures forced the orchestra to reschedule its Liberty Lake concert. The symphony sets up a rain/temperature date for the concerts, just in case.

The outdoor setting can also pose problems for the audio engineer, who travels from Eugene for the concerts.

When setting up the speakers throughout the park, in order to anticipate time delay, the engineer has to calculate how long the sound waves take to travel from one set of speakers to the next, ensuring the sound waves line up so that there is no echo or fuzziness, Cotter said.

But no matter the challenges they face, the members of the symphony perform at their best, knowing the importance of the Labor Day weekend concerts.

“When you have five or six thousand people sitting there, that’s a lot of familiar audience members, a lot of potential audience members and maybe people who hear us once a year,” said conductor and symphony music director Eckart Preu. “Maybe this one time they will say ‘You know, maybe I’ll come back. I’ll check them out in the hall instead of just getting that one show a year.’ ”

Both Labor Day weekend concerts, Saturday at Pavillion Park and Monday at Comstock Park, feature the same set list, a mix of patriotic songs and previews of what to expect from the symphony’s upcoming season.

“Even if you don’t normally go to an orchestra concert, there’s something in our season lineup that you will be looking forward to and didn’t even know it yet,” Cotter said.

The concerts kick off, appropriately, with John Stafford Smith’s “The Star-Spangled Banner” and close with Pyotr Ilyich Tchaikovsky’s 1812 Overture.

“That has been done for I don’t know how many decades,” Preu said of closing with the 1812 Overture. “I dared once not to do it, and I learned my lesson.”

In between the patriotic works, which also include George Frederic Handel’s Music for the Royal Fireworks and Bob Lowden’s Armed Forces Salute, the symphony will perform pieces that will preview its upcoming season.

To preview a collaboration with the Coeur d’Alene Opera on “Carmen,” the symphony will perform Suite No. 2 from the Georges Bizet opera.

To preview a collaboration with Spokane Civic Theatre on “West Side Story,” the symphony will perform “West Side Story” composer Leonard Bernstein’s Overture to “Candide.”

“Star Wars” composer John Williams’ “Throne Room End Title” and selections from George Gershwin’s “Porgy and Bess” also make an appearance, as does Camille Saint-Saëns’ Danse macabre, Opus 40 and Julius Fučik’s “Entrance Of The Gladiators,” Opus 68.

“It’s a diverse, fun mix of things,” Preu said. “There’s not necessarily a logic to that, because it’s a pops concerts. It doesn’t have to be logical. It just has to be emotional, and it has to be fun.”

Adding to the fun is the party atmosphere the audiences bring to these concerts, which Preu sees as social experiences where friends catch up with one another.

He also sees events like the Labor Day concerts as cultural experiences, opportunities to make classical music more accessible.

“What we’re trying to do is we humanize symphony,” he said. “We humanize classical music, and we also humanize the concert experience … I think there’s a lot of people who are not quite sure what this is like and I think this is a way of getting people familiarized with what we do and how we do it and what kind of people we are.”