The Rural Fire Authority says it could take another two days to contain a blaze which has destroyed almost 600 hectares of farmland and forest in Marlborough.
Fire crews, helicopters, bulldozers and excavators have been battling the fire since it started four days ago.
The incident controller John Foley said steep terrain and hot spots had hampered efforts but they hoped to have containment lines in place by tomorrow morning.
He said the fire had a perimeter of about 16 kilometres and it would probably take another 48 hours for ground crews to fully contain.
All helicopters have been stood down and the authority will assess whether it can scale back its crew on site after an aerial survey tomorrow morning.
Northbank Rd has been reopened to residents and logging companies.
Firefighters have had to cope with strong winds and temperatures of up to 29 degrees Celsius today.
Forestry clean up could reduce fire threat - mayor
The Mayor of Marlborough says better cleaning up of forestry wastage sites is needed to reduce the threat of heat-induced bushfires.
The debris from felled trees - known in forestry as skid sites - can ignite in extremely hot weather.
Mayor Alistair Sowman said there appeared to be a strong connection between skid sites and recent fires.
"The suggestion the current fire was started from a skid site, the one earlier last week was, there was another one on Thursday that was started from a skid site, we need to look at logging practices.
"There are the major causes of our fires, we need to change the practise quickly."
Mr Sowman said there were many skid sites throughout the province, and bits of steel left behind could also be contributing to fires.
He said foresters did all they could to limit fire risk.
Forest Owners Association chief executive David Rhodes said the process could always be improved, but it was not practical to dispose of the debris anywhere else.
He said foresters did their best to make sure debris was dumped in one pile at the sites.
The Rural Fire Authority said it did not know if skid sites or heaps of logging debris, were the cause of the fire.
Mr Hands said there were logging debris sites in the area where the fire was burning, and investigators were still looking into whether they caused it.
But he said the skid sites were old, and new or recent skids were generally the ones that could ignite in hot conditions.