Onerahi sit seven points clear after their outright victory over Kamo.
The competition leaders, helped by an unbeaten 79 from Todd Beehre and four-wicket bags for Tom Herman and Sam Walker, easily accounted for Kamo inside a day.
They now line up against Whangarei Boys' High School First XI, who have proven to be a good side across the season.
WBHS took first innings points against Maungakaramea last round with Chamodh Peiris (75) and Rory Christopherson (68) standing out.
In the last game, Maungakaramea host Kaipara Flats as both sides look to improve on their last efforts.
Kaipara Flats sit at the bottom of the ladder after struggling in their opening two matches against Kamo and City.