Otago Rural Fire Authority deputy principal officer Jamie Cowan said the Saddle Hill fire was burning out of control and 30 houses had been evacuated. There were unconfirmed reports of one house catching alight.
Strong winds - gusting up to 100km/h in some areas - grounded some helicopters trying to respond.
However, two helicopters with monsoon buckets and five fire trucks were on the scene.
Mosgiel resident Francis Murphy said his former farm was one of the properties ablaze.
"There is still a lot of smoke around and all the roads are blocked off, all I can see from here is just a bit of the hill and from the skyline the rest is smoke," he said.
Mr Murphy said the winds were dropping and it had started to rain about 4.30pm.
A large forest fire in East Otago yesterday threatened four homes near Dunback.
Otago deputy principal rural fire officer Graeme Still said by last night 20 firefighters and a few farmers had contained a more than 100ha forest and scrub fire about 3km southwest of Dunback.
Waitaki Rural firefighters said they would continue the fight overnight.
When firefighters arrived, the fire was being spread by winds up to 70km/h.
After noon, the fire threatened four houses near Dunback.
"It was very difficult conditions, very, very difficult," Mr Still said.
"It was touch and go there for a while, but we managed to keep it away [from the houses]."
Of the houses under threat, two were vacant and the residents of the other two houses were told to prepare to evacuate, but did not have to leave their properties, he said.
Three helicopters with monsoon buckets were deployed but when a fire started in Saddle Hill, two of the helicopters left Dunback to assist the battle in Dunedin.
In Dunback, the three helicopters were grounded when the wind picked up, but joined the fight when the wind speed dropped to about 30km/h later yesterday morning.
The helicopters had "worked the flanks", extinguishing any spot fires outside the main blaze to "pinch in" the edges of the fire.
A southerly wind change in the afternoon assisted the firefighters as they battled the blaze, he said.
No structures were damaged by the fire and no one was injured, he said.
The fire appeared to have started when a controlled burn about six weeks ago reignited in the windy conditions.
MetService meteorologist Ciaran Doolin said Dunedin reached 28.5C yesterday. One of the weather stations at Kaikoura rose above 32C, the highest recorded temperature for the month since 2005, and Timaru's 29C was the highest October reading in the South Canterbury town since 1962.
