Tuesday evening's scrub fire, the largest over the period, required three helicopters, three appliances and more than 30 personnel from the Roxburgh and Millers Flat volunteer brigades and the Otago Rural Fire Authority.
Roxburgh Chief Fire Officer David Rooney said despite the run of fires being unusual, none was suspicious.
It was believed a combination of factors, including high winds, heat and ''very, very dry'' conditions in Central Otago, were to blame.
Crews fought the blaze on Tuesday for about three hours after it started about 7.15pm.
''We were lucky the winds were changing and it began back-burning. We had very high winds when we first arrived but they changed when we were there for about 15 minutes and sort of helped us.''
Helicopters came from other parts of Otago to help control the fire, one spotting while two others operated monsoon buckets.
Despite the size of the fire, which burned through farmland and long grass, it was not too challenging to put out, he said.
That fire and another last Friday were believed to have started when high winds caused power lines to fall.
Investigations were continuing.
Many of the eight fires the Teviot Valley-based Roxburgh and Millers Flat Volunteer Fire Brigades had attended were smaller and caused by factors such as spontaneous combustion of green waste and controlled burning getting out of hand.
Mr Rooney said although brigades from the Teviot Valley had been busy, it was good for team morale.
He did not believe it was putting stress on any of the crew members, and he had not received any complaints.
Central Otago is under a restricted fire season, with the fire danger rated ''extreme''.
