Stronger winds predicted on Sunday afternoon are driving the firefighting strategy on day six of the Tasman district forest fire.
Fire and Emergency New Zealand rural regional manager John Sutton on Sunday morning said a control line had been established around the now 23000-hectare fire, made up of bulldozer lines, existing road lines and riverbed.
"We're probably in the best position we possible could be ... prepared for this wind event," he said.
"We have all the resources we need [that] we can possibly put in the pressure points and we're anticipating that wind to start progressing increasing from probably early afternoon.
"It's going to test us. It probably depends on whether the wind exceeds predictions or not."
Sutton said he believed the firefighting team would be able to control the fire "up to a certain threshold".
"I have confidence that we're able to do that," he said.
That threshold was up to about 50kmh. "It's how far it goes beyond that and for how long."
Ground crews would have to be pulled out if the winds topped about 50kmh.
"We can't put people in front of that fire," Sutton said.
The wind also reduced the effectiveness of the helicopters "and it gets to the stage where we are unable to use the aircraft".
Asked about the safety of Wakefield, Sutton said it was "OK at the moment".
"We'll be challenged if this wind exceeds 50kmh."
The fire was now "probably less than 2km" from Wakefield, progressively moving down the to river flat area.
"It will reach the river flat," he said, adding he expected that to happen sometime on Sunday afternoon.
"But that's not all bad; it's easier to fight fires on river flats than on hillsides, but the limiting factor will be the strength of the wind and whether we can actually put people in there to fight it."
Firefighters have been on the ground since Tuesday.
The police cordon set up at the edge of Wakefield.
John Sutton, Regional Manager of Fire Emergency New Zealand, during a press briefing on the fire.