The Otago Rural Fire Authority has declared a prohibited fire season in Central Otago.
Otago is New Zealand's driest region, with Central Otago as the worst affected by dry weather despite recent spring rain.
The Rural Fire Service said there had been fires in recent weeks caused by fireworks and permitted burns, which were not monitored.
Principal rural fire officer Stephanie Rotarangi said she believed it would get worse as the summer continued, with a strong El Niño weather pattern predicted.
A total ban on lighting fires in the open air is now in place but enclosed gas barbecues are still permitted.
House saved from blaze in Canterbury
In Canterbury, meanwhile, the Fire Service has saved a house being destroyed by a fire by using helicopters with monsoon buckets.
Ten fire engines responded to the fire on Dunsandel Brookside Road shortly after 11am.
Fire Service spokesman Brent Dunn said the fire started in a hedge then spread to a calving shed, which it destroyed. There were no stock inside, he said.
Mr Dunn said two helicopters were used to stop the fire reaching a nearby house, and the fire was under control.