Manawatu love to throw the ball around but the conditions didn't invite such play as they came close to scoring a much-needed try in the second half but they were repelled by a desperate Harbour side.
Halangahu was useful for Harbour and directed play astutely in the wet, while they were well-served by a passionate front-row.
You could tell how much this result meant to Harbour as they vigorously supported each other every time they forced an error from Manawatu or won a penalty.
Former Manawatu man Hayden Triggs was industrious for Harbour and showed his veteran experience in the lineout as he provided a calming influence.
Despite the loss, Manawatu remained at the top of the Championship standings and they will look to bounce back when they host Southland next week.
Harbour's next outing will come against Auckland at Eden Park next weekend.
Finally: The fifth time was the charm for Harbour who finally registered their first win of the 2014 campaign. Can they build from here?
Full-credit: Harbour skipper Bryn Hall played a full-game here and was useful for the home side as they were able to enjoy some rare success.
North Harbour 24 (Luke Devcich, Pita Ahki tries; Daniel Halangahu 4 pen, con)
Manawatu 13 (Callum Gibbins tries; Otere Black 2 pen, con)
halftime: 11-10