Civil Defence say the growth of the fire has slowed with lower temperatures and more moisture in the air but say the situation may change.
The Tasman fire that started yesterday afternoon in Pigeon Valley has doubled in size over more than 24hrs and spread to cover 1900ha within a perimeter of 22km.
More than 230 homes have been evacuated or self-evacuated with people registering with the Civil Defence Centre in Wakefield.
A second fire has broken out this afternoon on Rabbit Island - it covers up to 10ha.
Overnight 12 crews fought the blaze on an increasing front protecting as many structures as possible and minimising the burn on grasslands.
There have been no reports of injury or death.
More than 40 horses have been evacuated.
At least two homes have been lost in the fire.
More than 230 properties in the vicinity of the mammoth scrub fire rampaging its way across the Nelson region have been evacuated.
The fire which started in Pigeon Valley around 2pm on Tuesday now covers 1900ha with a perimeter approximately 22km in size.
In a statement, Tasman District Council said fire crews will be active throughout the night and there will be a community meeting tomorrow morning at 9am.
Fire and Emergency New Zealand incident controller John Sutton said it had been a good day on the ground for crews taking on the fire.
"We've had favourable weather and fire behaviour. Currently, 48 crew, 14 aircraft and about 10 pieces of heavy machinery are fighting the blaze," he said.
"We have no injuries or confirmed loss of property."
The direction the fire will head in is difficult to judge, he said, and can change quickly depending on weather conditions and temperatures.
Similar weather from today is expected tomorrow which should help efforts to contain the raging fire.
"Tomorrow should be a similar weather pattern – that will be in our favour. It will help us contain the fire if there are changes to the weather later," Sutton said.
"At the moment we are focusing on containment. NZDF and DOC crews are arriving tomorrow as well as a couple more aircraft. Heavy machinery will work on fire breaks."
Ground crews remain in place in Eves Valley, Redwood Park and Pigeon Valley as helicopters work to protect homes and manage the fire.
Bulldozers are also working on containment lines in key areas, the Tasman District Council statement said.
Earlier today, Nick Smith reported two homes had been lost as a result of the large scrub fire.
The MP for Nelson returned to the area from Waitangi earlier today and said around 2000ha had been burnt, including two homes.
And other residents are worried for their own homes as they head into the second night of the fire.
David Horncastle lives in Pigeon Hill and his family home is next to a Carter Holt Harvey tree plantation.
"Last night the flames were really, really high. The wind was coming straight at our house but changed direction. I called up my friend Malcolm to help make a fire break with his digger.
"At 8pm the helicopters get parked up, they can't fly at night and don't start again until 6am in the morning. If any fires spark up in the night then we are on our own so we are also evacuating."
A farmer ploughing his fields yesterday afternoon allegedly sparked the fire in Pigeon Valley.
Helicopters are attacking the fire spread across 20km from the air as Civil Defence declares a state of emergency and more than 170 homes have been evacuated or self-evacuated. More than 40 horses have also been evacuated from farms and lifestyle blocks under threat.
The fire was sparked by a farmer discing [tilling] his dry fields at around 2pm up Pigeon Valley near Wakefield, about 30km south of Nelson, the Herald has been told by multiple sources.
"There is an inspector on the ground but it is going to be some time before an outcome is identified. [The] focus at this stage is managing the fire and helping the affected people," he said.
Meanwhile a second fire broke out today on Rabbit Island, close to Pigeon Valley where the original fire started yesterday.
Civil Defence Minister Kris Faafoi said the Tasman blaze was a local state of emergency and 170 properties had been evacuated.
Within that, the early number was that two houses had been damaged, he said.
Truck driver Kim Ponga also watched on, the immense fire was first brought to her attention in a flurry of sirens mid afternoon yesterday.
Ponga has lived in Richmond for about seven years.
"This is the first year we have seen a fire like this.
"This is the first year it has been so dry.
"I feel for the families."
Armadillo's director Tony Crosbie said his restaurant in Richmond was giving away free meals to volunteers - about 20 had come through the doors today.
As the fire raged last night and threatened properties, the Nelson Harness Racing Club, supported the local A&P Association, offered their stables at Richmond Park as a safe haven.
Horse trainer Brian Johnson, and vice-president of the Nelson Harness Racing Club, said he was at the track late last night when horses were being brought in at 10.30pm.
"They are most welcome to be here," Johnson said.
"Most of them come from lifestyle properties and are quite special breeds."
The company of other animals keeps them calm despite the foreign environment, the experienced horseman said.
Sheep, goats and other livestock were welcome at the otherwise empty stables, Civil Defence said.