Fire and Emergency says high winds have forced half of its helicopter fleet to be grounded as a wildfire near Twizel grows.
Seven helicopters with monsoon buckets had been battling the scrub fire at Pukaki Downs since this morning.
Fire and Emergency Mid-South Canterbury assistant commander Stephen Butler told Midday Report safety concerns forced half of the fleet to be grounded.
Six properties on Mount Cook Road were evacuated as a precaution and more residents have left of their own accord since the fire broke out on Monday night.
Fire and Emergency NZ (FENZ) assistant commander for Mid-South Canterbury Stephen Butler said no buildings had been damaged.
MetService has an orange strong wind warning in place for the Canterbury High Country until 10pm tonight, with severe gale northwesterlies and damaging gusts of up to 140km/h forecast in exposed places, particularly this afternoon and evening.
State Highway 80 is closed at the intersection with SH8 due to the blaze.
Waka Kotahi said no detour was available and asked people to avoid the area and to delay their journeys if possible.
Pūkāki ward councillor Scott Aronsen said the flames were ripping through a stand of wilding pines at the edge of Lake Pūkāki.
He said the strong winds that had been preventing firefighters from tackling it have died off, and in recent hours the blaze appears to have eased a little too.
The fire was burning strongly when he returned home around midnight on Wednesday, he said.
"It was just a raging inferno, had a fire front of probably around a kilometre, spread from an east-west direction."
Chris Rudge from Aviation Adventures lives about six kilometres from the fire and told Morning Report he had seen two helicopters leave the airport with monsoon buckets on Thursday morning.
"They'll be using those to the best abilities they can, rather than using people on the ground because of the high winds."
The fire was still "very active", he said.
"We have a large column of smoke heading into the sky and then sort of down towards Twizel."
The fire was getting into "standing trees so there's shoots of flame going up at least a hundred feet or more into the air when it hit the trees", Aronsen said.
He said six or seven helicopters were required last time there was a fire in the area and it was likely that number would be needed again to tackle this blaze.
If the wind picked up again this afternoon, the blaze could spread further, he said.
"There is risk if the wind blows from the north, straight down Lake Pūkaki towards Twizel, if it gets out into the open tussock country or some grasslands we certainly could have a bit of an issue."
Another man living close to Twizel also feared the massive scrub fire would spread fast in the strong winds.
Jason Swain, who lives about 15 kilometres away from the fire, said similar wind fanned the Ohāu blaze which destroyed 48 homes three years ago.
"That's probably the big worry, there's huge winds and we seem to be in the middle of the wind at the moment and that really pushed the fires around last time," he said.
Wilding pines and slash providing fuel
The issue of wilding pines had been growing in the area over the past two decades Aronsen said.
"Wilding pines are hard to control, they cost lots of money to eradicate and the writing's been on the wall for some time unfortunately, with the trees."
Rudge said that in addition to the wilding pines, slash from a 2020 fire in the same area was providing the blaze with fuel.
"They bulldozed down the burnt trees from last time and put them in rows and they're alight as well."
It had also been a fairly dry winter so there was also a lack of moisture in the ground, Aronsen said.
Rudge agreed it had been "quite warm conditions, particularly for this time of year".
He said there was a high of around 23 degrees in the area yesterday, with the temperature having already reached 19 degrees by 6am Wednesday morning - the hottest he could recall for September.
Spring blast brings strong winds, snow, avalanche warnings
Wild weather has caused damage to powerlines and flipped five vehicles on South Canterbury roads so far this week.
The strong wind gusts could make driving conditions hazardous, MetService said, with motorbike users and drivers in high-sided vehicles needing to take particular care.
In addition to the high winds forecast for Canterbury's high country, MetService has issued orange heavy rain warnings across the West Coast, Central Otago and Southland/Fiordland through until Friday.
Meanwhile, Inland Canterbury, Central Otago and Queenstown Lakes have heavy snow watches in place and the New Zealand Avalanche Advisory is warning of a high risk of avalanches in alpine elevations at Arthur's Pass, Aoraki/Mt Cook, Ohāu, Queenstown, Wānaka, Fiordland and Aspiring; with many of those areas' sub-alpine elevations also at moderate to considerable risk of avalanches.