It was an anxious night for residents in Wakefield, near Nelson, after they were told to be on high alert and ready to evacuate if necessary.
The evacuation warning still remains in place, as fire crews continue to battle the blaze in hot and dry conditions.
Dennis Bush King, the Tasman Civil Defence Controller, told Breakfast today's "weather forecast is not good".
1 NEWS reporter Kim Baker Wilson said "you can still see orange flames in the sky, a clear sign this fire is still going. Another uncertain day for firefighters and residents."
Civil Defence has told 1 NEWS there was unexpected fire growth last night, but fire crews are managing to control it.
Schools in Wakefield - a primary school and two early childhood education centres - will be asked to close today because of an expected weather change during the day. Officials do not want the road to be blocked in case the fire comes near.
Police and Civil Defence issued a precautionary warning last night, telling residents in the area north of State Highway 6, Wakefield between Pigeon Valley and Arnold Lane that they should start gathering essential items such as food, clothing and medication should they need to evacuate.
Authorities advised people to keep their mobile phones on them in case emergency services needed to contact them.
A spokesperson for Fire and Emergency New Zealand said the Nelson fire was most likely caused by agricultural machinery.
Fire and Emergency New Zealand's incident controller, John Sutton, told a media briefing yesterday that the most likely cause of the out-of-control blaze was a tractor towing discs in a rocky field.
"We've got a fire investigator working on that fire and at this stage it's almost certain it's as a result from a spark from agricultural machinery," he said.
He said the owner of the tractor was aware it was likely theirs and is "mortified."
Mr Sutton said that farmers in Nelson's dry conditions have been advised to suspend roadside mowing or any such operations likely to create sparks.
One house has burnt to the ground from the fire.
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