Hayley Coakes, Jimi Crooks and Tom Bracegirdle all sealed South Island titles in their respective categories.
Coakes defended her South Island open women's title with a win in Kaikoura.
She also won the Canterbury championships earlier in the series and finished in second place in the other three events.
"I've had pretty good results and have improved," Coakes said.
"Even though I won last year as well, my results have been better."
Coakes had built an unassailable lead before the Cold Water Classic, which allowed her to relax and surf at her best.
"I was a bit more relaxed but I still really wanted to win in Kaikoura."
She described the waves as "pumping".
"We couldn't have asked for better, really."
The opening two days were relatively sunny but the weather turned bitterly cold on the final day, with hail flurries making conditions uncomfortable.
Kaikoura surfer Levi O'Connor battled hail and even snow flurries to win the open men's event after scoring 5.3 on his final wave.
It was enough to push Westport's Antony Hema into second place by the tiny margin of 0.03 points.
Crooks claimed the under-18 South Island title with his win in Kaikoura.
It was his third win in six events.
Crooks, who has been surfing for about nine years, was in the same category last year but did not compete in all the events.
He was thrilled with his victory.
Bracegirdle also finished the under-16 series on a high, winning in Kaikoura and claiming the South Island title.
Dunedin's Leroy Rust won the men's longboard category in Kaikoura.
