The 20-year-old won the women's javelin with a 53.25m throw, well clear of Stef Wrathall, of Auckland, who finished second with 48.97m.
Peeters, who also won the national title a year ago with a 54.45m throw, started out with a 45.21m throw at the weekend, before gradually building as the competition went on.
While the sun shone at times, Wellington was peppered by heavy rain and wind throughout the three days of competition.
Otago's Felix McDonald battled the elements to win gold in the 110m youth hurdles and long jump, and silver in the 300m hurdles.
He managed a 6.78m jump in the long jump, comfortably beating second-placed Ben Collerton, of Canterbury, by 47cm.
However, his win in the 110m hurdles was a different story. McDonald had to fend off Collerton to win in 14.3sec, in a thrilling race.
He was on the other side of close finish in the 300m hurdles, after Southland's Patrick Taberner pipped him by .35sec.
The hurdle specialist wrapped up a successful weekend by winning gold in the 4x400m youth relay with Oli Chignell, Jacob Granger and Matthew Ogle, and silver in the 4x100m youth relay with Ogle, Granger and Schulyer Orr.
Hugh Mcleod-Jones, the year 13 Otago Boys' High School pupil who smashed the school's 43-year old senior shot put record recently, shone in another discipline at the weekend.
McLeod-Jones won the men's youth discus title with a 47.26m heave on his first and only legitimate throw.
Denzelle To'o, of the Cook Islands, managed a 49.83m throw but was not eligible for a New Zealand title.
Otago 800m and 1500m champion Ben Anderson snared a silver medal over his favoured 800m.
After qualifying for the final with a 1min 54.46sec run in the second of two preliminary finals, Anderson finished second behind Canterbury's Brad Mathas in the final.
The Caversham runner clocked 1min 51.35 in the final, outside his personal-best of 1min 49.69sec, which he recorded two weeks ago in Auckland. Mathas won in 1min 49.89sec.
Hanna English ran a personal-best 17min 48.55sec to win silver in the women's junior 5000m.
English, who is now based in Auckland and is concentrating on football, could not keep up with Canterbury's Gabrielle Gray, who won in 17min 12.91sec.
Next year's nationals, which double as Olympic trials, will be held at the Caledonian Ground in Dunedin on March 11-13.
National championships
Otago medallists
Gold: Tori Peeters (senior javelin), Christina Ashton (100m junior hurdles), Felix McDonald (110m youth hurdles and long jump), Hugh McLeod-Jones (youth discus), Anna Grimaldi (AWD 100m, 400m, long jump), Holly Robinson (AWD javelin), men's 4x400m youth relay.
Silver: Ben Anderson (senior 800m), Hanna English (youth 5000m), Madaline Spence (400m senior hurdles), Elizabeth Jones (junior hammer throw), Bradley Tarleton (junior hammer throw), Felix McDonald (300m youth hurdles), Jacob Granger (youth triple jump), Richard Nelson-Parker (AWD long jump), women's 4x100m youth relay, men's 4x100m youth relay.
Bronze: Daniel O'Shea (senior 400m), Stephen Isaac (senior 110m hurdles), Richard Nelson-Parker (AWD 200m), men's 4x100m junior relay.
