The 20-year-old broke her previous Otago age-group record with three of six throws at the interclub meeting at the Caledonian Ground on Saturday.
The last of her six throws was an impressive 53.18m effort — almost 3m better than the 50.50m record she held going into the meeting.
Only four women have thrown the hammer further in New Zealand this year, so Shepherd-Oates continues to climb her way up the rankings.
The other notable performance came form veteran athlete Alison Newall.
The 60-year-old pole vaulted 2m to break the national record for her age grade.
She also broke the Otago triple jump record for her age bracket with a leap of 7.39m.