Firefighters battling a large blaze in Marlborough are trying to make the most of a calm period before high winds whip through the area.
Fifty firefighters and nine choppers are at the scene after fire broke out in dry vegetation in a private forestry area of the Waikakaho Valley yesterday.
Four water tankers and three fire trucks are also there and flames have so far burned through 450 hectares.
A Marlborough Rural Fire Authority spokeswoman said the choppers were back in business at first light today.
"It's still burning pretty hot."
Five properties in the area were evacuated yesterday and people in a further 20 self-evacuated. Police officers were checking on those houses again today.
It's thought the fire would probably burn through 600 hectares before it was brought under control, but the weather forecast in the area was not looking promising, with a high of 27C predicted.
"It's hot and we've got a severe wind warning coming up later today. That means 100 knot plus winds. It's going to be very difficult conditions for the chopper," the spokeswoman said.
The wind wasn't blowing at the moment.
"They've got a window of a couple of hours to really get into it."
So far nobody has been injured in the blaze and no houses have been damaged, although a bulldozer and a digger from the forestry sites were burned.
Last night, ground crews kept an eye on "a couple of areas of concern and [were] monitoring any threats to properties in that area," a Southern Fire Communications spokesman said.
The Airways Corporation has issued an advisory against all aviation north of Woodbourne Airport.
The fire was thought to have come within 60 metres of the most vulnerable house.