The defending champion made it a memorable weekend on his month-long road trip around the country by beginning with a South Island Supercross title win on Saturday in Motueka.
On Sunday, he retained his fast form, following up with placings of 1-2-1 in the three national races to overtake early series leader Mason Phillips (Mt Maunganui).
Drizzle had turned Motueka's Rat Track soggy, making taking off and landing the jumps challenging, Columb said.
"When you are jumping 90 feet (27m) and it's slippery conditions, you have got to have the bike pretty straight."
Columb was No 2 after the first round in Timaru on Wednesday, so to now be six points ahead going into the Tokoroa-hosted third round on Saturdaywas a bonus, he said.
"It's not much but I've turned it around.
"Timaru didn't really go to plan and I struggled there."
He will be hoping to extend his lead going into the fourth and final round a week later to make up for coming home with the runner-up trophy in the 2009 New Zealand Motocross Championships.
Bay of Plenty rider Ben Townley dominated the evening's racing, emerging victorious in his trio of MX1 races.
The Kawasaki ace has been on the comeback from injury but demonstrated he was nearing full fitness by edging out Cody Cooper, of Mt Maunganui, and New Zealand MX1 motocross champion Justin McDonald, of Christchurch.
In close racing in the junior grades, Wanganui's Tom Managh moved up from second overall and 11 points behind Rangiora's Isaiah McGoldrick, to equal him on first in the 250cc class standings.
In the 85cc category, Micah McGoldrick, younger brother of Isaiah, stretched his points lead with 1-3-1 results, while Pahiatua's Scott Sowry impressed with three runner-up finishes.
Columb is staying on the road this season and training on the supercross tracks of his international riding friends Josh Coppins, in Motueka, and Townley, at Mt Maunganui, between events.
