SYJB returned from the youth jazz event after winning gold and a runner-up overall award at the contest.
"We were really proud to achieve a gold award and the runner-up best ensemble award," the band’s musical director Emma Jarman said.
"The standard at the competition is always really high."
The group’s diverse programme included the Bruno Mars’ hit Treasure, and Wandering Eye by New Zealand band Fat Freddy’s Drop.
"Judges commended the SYJB on how well we knew our charts, our communication together, the great selection of pieces we chose, and how entertaining they were to watch," Ms Jarman said.
The accolades kept coming for SYJB when two students were selected to join the all-stars band.
Trombonist Sam McGregor, 17, said it was "so exciting" to be invited to play in the all-stars band.
"Working with [musician] Dan Hales and the other tutors was an absolute highlight."
Bandmate Nate Sutherland was equally thrilled by the chance to play with his peers and to learn from his mentors.
"Playing jazz alongside all the talented musicians at Southern Jam was an awesome experience," the 18-year-old said.
The opportunity of having a workshop with [jazz drummer] Lance Philip was hugely inspiring and drastically improved my drumming technique."
The band has also been selected for the finals of the New Zealand JazzBand-It youth jazz contest.
"JazzBand-It was set up by Rodger Fox four years ago, and is a national contest focusing on performing New Zealand works," Ms Jarman said.
"Out of over 50 bands that entered this year, we have made the top 10 national final, and are one of only two bands from the South Island."
The winner will receive $6000 of musical equipment from Musicworks NZ plus a recording and music video, valued at $4250.
The second and third-placed bands will receive $2500 and $1500 respectively, of musical equipment.
Yesterday SYJB held a musical bingo fundraiser to get the band to the final in October.
"We hoped to raise as much as possible because it’s roughly $1000 per student to attend the finals," she said.