A large vegetation fire in Whangārei Heads in Northland is expected to take three days to put out.
Two properties have been evacuted, one which self-evacuated and the other which continues to be threatened, Fire and Emergency says.
Structure protection at the property will take place overnight.
Incident controller Graeme Quensell says the fire, which is now 20 hectares, escalated quickly.
Crews were called shortly at 12.30pm Thursday to the blaze on Whangārei Heads Road between Onerahi and Tamaterau.
"We currently have five helicopters on site, four with buckets and one acting as observation and they will be operating until sundown.
"If at any point residents in the area are worried about their property, they should self-evacuate and call 111."
Fire and Emergency's Northland District manager Wipari Henwood earlier said the fire was burning in a "problematic area", with numerous access points.
It has advised people affected by the smoke to close windows and doors and reduce outdoor exercise. Air conditioning should be switched to 'recirculate' or turned off and pets should be kept inside with clean food and water.
The cause of the fire was not yet known and will be investigated.
One resident said the fire was scary and bigger than she had seen in previous years.
The resident, who did not want to be named, lives about a kilometre from the fire.
She said she could see flames and several helicopters pouring buckets of water onto the fire.
They have had bush fires previously, she said, but not at the scale she saw Thursday.
Ryan Houbar lives near Whangārei's port and said the smoke from the fire had been drifting over from across the harbour and was visible from where he was at Port Nikau.
"There's this big plume of smoke coming off it and it's coming down through where we are down at the port and it looks like quite a large fire. We can definitely smell it all down here and it's getting pretty hazy down here."
The weather has been mostly dry for a couple of weeks, with all but a few instances of light showers, he said.
Paul Doherty, a church deacon in Onerahi, said he was one of about a dozen people at a lookout at the end of the Whangārei Airport runway.
From there they could look directly across the water to the fire at Waikaraka.
He could see several helicopters at work, scooping water from the harbour and dumping it on the fire.
"There's smoke billowing all across the airport, and down the other side of the harbour towards Oakleigh. It seems to be less intense than it was, which is a good sign."
Through the haze he could see a number of homes on the hillside but they did not appear to be in immediate danger.
Weather outlook
Dry, breezy weather in Northland is largely set to continue over the next 24 hours.
Metservice meteorologist Mmathapelo Makgabutlane says the wind around Whangārei Heads will ease Thursday afternoon, but pick up again on Friday.
While there was a chance of a shower on Friday, she said it likely won't be enough to put a fire out.
Whangārei Airport remains open and airport duty manager Gareth Worswick said the fire was close, but an easterly wind was blowing the smoke away from the runway so visibility remained good.
Road reopens
The Whangārei District Council said Whangārei Heads Road had reopened but with a 30km/h speed limit near the Beach Road intersection at Onerahi.
Motorists were advised to drive with caution, be prepared for smoke, and give way to emergency vehicles.
Helicopters would be operating at first light on Friday.
People wanting to take another route to Whangārei Heads can use Mount Tiger Road.
Whangārei Heads Road was closed earlier this afternoon at Waikaraka, between Onerahi and Tamaterau.