Central Otago principal rural fire officer Owen Burgess said with all the recent rain and snow, the ground was like a swamp and he turned the Roxburgh and Millers Flat volunteer fire brigades around, calling in two helicopters from Helicopters Otago instead.
The fire, on the Knobby Range, was lit about noon on Thursday by a farmer to get rid of rank grass and tussock, Mr Burgess said.
''But it had a mind of its own and decided to keep going.''
He said it was ''freezing cold'' up there and slightly windy.
Despite the cold and the marsh-like ground, the fire kept burning, even underneath snow.
''Fire is a very strange animal in the right conditions - it will burn under and over anything.''
Mr Burgess said the helicopters were able to pick up the ground water and use it to ''douse the head of the fire, the flanks and the perimeter'' so although the fire was left burning, it was contained.
''It's the best way, instead of spending hours and hours putting it out.''
It burnt an area of about 100ha. Mr Burgess said the farmer would bear the cost of the three-hour firefighting effort, but he was doing the right thing in burning off excess vegetation, which reduced potential fuel for fires.
It was an open fire season in Central Otago and the farmer lit the fire under the right weather conditions, Mr Burgess said.
''The only [other] thing I think that farmers could do is put a fire break in where possible so it only burns to a certain area.''
