Firefighters continue to work on the perimeter of the Great Barrier Island fire which flared up overnight but stayed within containment lines.
The blaze has burned across 112ha, with ground crew and thermal imagery used to identify hotspots.
Additional fire crews have been recruited from Rotorua and Nelson to relieve exhausted Auckland crews.
"The fire is contained but not out and there's still a lot of work to be done," said National Rural Fire Officer Murray Dudfield.
Weather conditions are favourable for this ground-based operation today, but increased winds are expected tomorrow and on Saturday making further work to strengthen containment lines a top priority, said an Auckland Council statement.
No properties have been damaged and residents who were evacuated from the Okupu Ridge area have returned to their properties.
Additional supplies were shipped to the island overnight.
Operations at Claris Airport have been affected but Okiwi airfield is still operational and extra support staff are being sent in.
An independent fire investigator will be on site today to help establish the cause of the fire.
Mr Dudfield said it was a similar situation with a large fire on the Pouto Peninsula in Northland, which covered about 200ha.
Firefighters had contained the blaze but were attempting to completely extinguish it today.
There were four large scrub fires in different parts of New Zealand yesterday.
"Soil moisture levels are below normal so when you do get a fire there's a lot of work to be done to saturate the fuel and soil with water," Mr Dudfield said.
"The last three summers have been quite quiet for us and this is going back to what we used to get about five years ago."