Up 12-3 at half-time and turning to face the harsh weather, Whanganui struggled when North Otago started to get the shine of the whistle, as winger Abel Magalogo slotted a couple more penalties, and then after a fumbling first-half, fullback Levi Emery redeemed with a brilliant kick-ahead try when Whanganui spilled possession on the attacking 40m.
Leading 16-12, North Otago would have been content to use the wind to kick for the corners for the rest of the game, but then the warm sun came back out, allowing Whanganui to play a little more expansively.
The visitors also started to falter under the pressure – with centre Hayden Todd and Emery both missing penalty kicks, and then spilled passes and dropped bombs let Whanganui get into attacking position, with Todd also sin-binned for a professional foul.
Winger Alekesio Vakarorgo finished off a brilliant team try in the corner after multiple forwards delivered crisp passes following centre Kameli Kuruyabaki's line break.
Prop Viki Tofa spun through two tacklers to offload to No8 Mathew Taula-Fili, who in turn found reserve prop Gabriel Hakaraia, who sent flanker Jamie Hughes ranging wide and his great pass saw Vakarogo flash over at the corner flag.
Then, with 10 minutes left, a clever ruck dash and chip ahead by halfback Lindsay Horrocks left North Otago defending a 5m scrum, and after only just coming onto the field, a fresh Semi Vodosese dashed blindside off the back to beat Magalogo clean and dive in at the corner.
Turning down easy three point chances to go for the winning seven-pointer, rather than trying to get back quickly from a restart, North Otago drove from two attacking lineouts, but the defence held.
Horrocks got into the maul to hold up the ball carrier for a turnover, and from the scrum, Whanganui showed great discipline to carry repeatedly inside their own 22m for the last two minutes, then boot the ball out for full-time.
Although not the preferred Meads Cup, claiming some silverware was a fitting farewell for retiring coach Jason Caskey and departing captain Campbell Hart.
"We were under pressure when we lost that second game and we've had to fight," said Hart.
"We've had to play our best rugby every single week, and so we finished as high as we could in the end and did the job today."
Other than the lost ball leading to Emery's try, Hakaraia had a fine match in his comeback, having to get on early when Hadlee Hay-Horton was injured.
Hart likewise stepped up in the lineout when lock Josh Lane had to depart hurt, while Kuruyabaki's break leading to Vakarorogo scoring as well as stopping Todd over the try-line in the first half proved decisive.
Best of the visitors was hard running No8 Sean Jansen, big prop Melikisua Kolinisau and the crafty veteran Ralph Darling, who was introduced after 31 minutes.
"We were looking at the weather and we didn't think there was anything coming, but Caskey, he knew the weather was coming so we had to prep for it a little bit," said Hart.
"The line speed that [North Otago] brought in the first half was intense – we couldn't really get anything going or we were always under pressure.
"We just needed to stay composed. We've known all season we could score from anywhere and we had that ability.
"Alekesio scoring over there was probably a good team try in the end."
Vodosese appeared to have gone rogue when he dashed blindside with no support, but Hart explained they backed the young Fijian in a one vs one challenge that close out.
"That was a planned move. That's what we asked him to do – Lindsay would go one way, he goes the other. It's worked at club level and it worked for them today."
In his last game, Caskey had faced the 'coach-killer' decisions – instructing the side to prepare for wet weather despite the dry track and blue sky, then later subbing out in-form kicker Robinson for a hard ball-runner in Timoci Seruwalu.
He came up trumps.
"The guys, they didn't think it was going to rain at all. So, there you go, the forecast, quite often, can be right.
"Campbell said, before the game, 'what do you think?' So I said, 'if it does pack up, sometimes it's best to get the points on the board, to use the wind first', which we did.
"North Otago chipped it away pretty quickly in that second half.
"We had to work pretty hard, and I'm proud of the boys, the way they managed to get two tries into the wind was a telling factor – they had to work really hard to get that opportunity.
"We were probably a little lucky that the weather did clear up a bit and let us play a little bit in that last 20, because if it had stayed hammering down as we got behind, I think it would have been bloody hard to pull that back."
Steelform Whanganui 22 (Alekesio Vakarorogo, Semi Vodosese tries; Ethan Robinson 4 pen) bt North Otago 16 (Levi Emery try; Abel Magalogo 3 pen, con). HT: 12-3.
