The wind was a factor at Kettle Park but Harbour still managed to blow a 20-10 halftime lead.
The Hawks will be left ruing some poor discipline which saw both Naulia Dawai and Hale T-Pole both issued yellow cards.
Dawai was in the sin bin when Louis Tili scored a try for Dunedin in injury time to level the score 34-34. First five-eighth Tim Cossens drilled the conversion from near the sideline to clinch victory.
Harbour played with the wind in the opening half and scored tries through winger Sala Halaleva, hooker Sekonaia Pole and centre Aleki Morris.
Morris and Pole added one apiece in the second spell, as well.
Dunedin hooker Sam Anderson-Heather had a strong game and scored after his side had been hammering away at the Harbour line shortly before the break.
He barged over for his second following the resumption. Highlander Gareth Evans scored two second-half tries to help his side get back into contention.
Lock Harry Dodds stood out in the lineout for Dunedin, while former Green Island midfielder Fapene Popoali’i showed promise.
Evans delivered a quality performance, as was to be expected, Morris found space in the midfield for Harbour and halfback Tala Fagasoaia also impressed.
There were lots of missed tackles and errors during the game, though, so plenty to work on for both sides.
Video highlights from the game