The visitor's sideline-to-sideline transfer rate was excellent, playing up-tempo and trying to keep Taihape's vaunted forward pack out of the equation as much as possible.
Centre and former Taihape player Kameli Kuruyabaki, winger Peceli Malanicagi and try-scoring fullback Josaia Bogileka looked to sweep through down either touchline, and when the home side infringed when trying to stop the momentum Tremayne stepped up to coolly slot home three penalties.
However, when they could get some traction and pull the visitors back into the set-piece, Taihape's forwards offered a harbinger of what was to come later in the second half, as black clouds gathered behind the grandstand.
Prop Gabriel Hakaraia would score two tries in the first half and as it got wetter he got hungrier, ultimately finishing with four tries as he rockets up the season's scorer list.
The rain descended right on halftime and Taihape immediately responded.
First-five Dane Whale, ultimately scoring 19 points, took over where Tremayne left off with pinpoint kicking, while Hakaraia and double try-scoring No8 Ben Whale climbed through slipping tacklers on the carry.
Taihape had the ability to bring on fresh Steelform Whanganui wider-squad loose forwards in Regan Collier and try-scorer Jamie Hughes, while Ngamatapouri, who had a couple of forwards out with Covid-19, could not match that depth.
The home pack, led by lock Matt Brown, moved up swiftly on the slowed Ngamatapouri backs for some bone-rattling tackles, while the ball slipping from hand on their returns from Dane Whale's long kicks proved costly.
Two tighthead scrum wins and domination of the lineout meant Taihape just camped in Ngamatapouri's half for all but six minutes of the second stanza, raising an unanswered 40 points before the sun returned for the last 10 minutes, which was when Hakaraia completed a rare quartet of tries for a front-rower.
"It was a 20-30 point wind out there early, so we just had to grind out that first 40, which I thought we did bloody well," said satisfied coach Tom Wells.
"Once we played with the wind in the right areas, we just stuck to our structures so well.
"So proud of the boys – our carries, our support play – there was a lot of ticker, which was good to see.
"The forwards got a roll-on but Dane's kicking game was spot on. The kick-chase was fantastic, which it has to be against these guys."
While all of the former Ruapehu players Taihape have picked up this year have contributed well, it is Hakaraia unquestionably who has made the biggest impact – scoring in virtually every game.
"Gabe's like-for-like, obviously Hadlee [Hay-Horton's] not here this year. He's loving his time here and he's doing a great job, so we're proud of him," said Wells.
For Tremayne, it had been a tough afternoon to bear witness - that after probably Ngamatapouri's best half of football this campaign the momentum literally washed away.
"Just conditions in that second half. Our shape was quite good in the first half but we had four or five guys pull out with flu before the game," he said.
"Our bench players probably haven't played enough rugby to keep our structure, so hopefully they learnt from this and they can be better from it.
"But we just struggled with our structure come that second half. Trying to play tight rugby was just not us.
"If we'd known [the weather would turn] from the start of the game, I would have played the first half into the wind when the weather was dry, but we didn't know that."
Taihape 59 (G Hakaraia 4, B Whale 2, D Whale, J Barrett, J Hughes tries; D Whale 7 con) bt Ngamatapouri 16 (J Bogileka try; B Tremayne 3 pen, con). HT: 16-12 Ngamatapouri.
