A total fire ban is across Otago as authorities warn of extreme risk of a major blaze which could take weeks to put out.
Dry conditions and significant fuel would cause any fire to spread quickly, Otago Rural Fire Authority principal rural fire officer Stephanie Rotarangi said.
Any fire, whether a controlled burn or from a chainsaw spark, could cause widespread damage.
City Forest chief executive Grant Dodson said a fire in scrub or forestry would take a "major effort in expense and time to put it out".
"It's going to do a lot of damage and take weeks, not days, to put out," he said.
A total fire ban began in Central Otago last month but the restrictions have been extended from Oamaru to Papatowai. A similar ban comes into force in Canterbury tonight.
Niwa predicts warmer and drier-than-normal weather is likely to continue for the next three months.
MetService's January outlook suggests some rain mid-month with a brief spell of cooler temperatures for the eastern South Island before warmer conditions by month's end.
Dr Rotarangi said an accidental fire was less likely to start during the cooler temperatures and light rain. But it would not change the fire risk, based on factors such as grass curing, fine fuels and drought codes.
High fire danger is predicted today, with temperatures in the mid-20s across the region.
"We are set for some hot, dry, windy days," Mr Cowan said.