Fire and Emergency NZ said there are 23 appliances, 15 helicopters and two fixed-wing aircraft focused on retardant drops on the Port Hills.
But two helicopters have been diverted to View Hill, Oxford, to help battle a hillside fire.
The two choppers are helping six fire crews to dampen down hotspots, particularly around rough terrain.
An Oxford resident told Chris Lynch Media the helicopters arrived at the scene before 10am.
The resident also said there are currently “view strong winds” in Oxford.
Meanwhile, another fire threatened a building in the Selwyn district this morning.
Firefighters responded to the grass fire near Rolleston shortly before 9am on Thursday.
- What you need to know about the Port Hills fire
- Couple who lost home in 2017 fire evacuated again
- 'Disaster tourists' told to stay away
FENZ shift manager Alex Norris said the blaze had threatened a structure, though he was not sure if it was residential or commercial.
He said firefighters had now brought the fire under control.
Four fire trucks and a tanker were sent to the blaze near Manion Rd.
Waka Kotahi NZ Transport Agency says smoke was reducing visibility on State Highway 1, north of Rolleston, between the intersections with Berketts Rd and Robinsons Rd.
However, at 10.30am SH1 was fully open, visibility had improved and northbound traffic congestion was easing.
