Fire and Emergency New Zealand on-call Otago area commander Phil Marsh said most of the fires remained under investigation and there was nothing to suggest any link between them, though it was unusual to have so many close together.
Fire crews were coping well but the resources of fire investigators had been stretched, he said.
He issued an appeal for those in the South to give themselves the best chance to stop fires, or stop them starting, as winter settled on the region.
"Make sure you have working smoke alarms, empty your ashes into metal containers, get your chimney swept and please keep looking while you're cooking.''
The first of yesterday's four fires began in a million-dollar central Dunedin home.
Firefighters were called to the home in Stoutgate, off London St, shortly before 6am, and four crews managed to stop the blaze fully engulfing the two-storey house.
One person suffered severe smoke inhalation and burns when they went back into the home and tried to douse the fire with a hose.
They were taken to Dunedin Hospital in a serious condition.
Fire risk management officer Scott Lanauze said the home had been filled with thick, acrid smoke after the fire began in the front, main room.
Its cause remained unknown, but a valuable lesson could be taken from the incident, he said.
"When you get out, stay out.''
Later, at a home just north of Milton, near State Highway 1, a fire started about 10am in a laundry of a home when all occupants were away.
Fire risk management officer Mark Bredenbeck said thanks to the quick work of neighbours who raised the alarm and the speedy arrival of a fire crew from Milton, later joined by one from Balclutha, the fire was contained to the laundry.
He concluded the fire had probably started in the washing machine due, to a malfunction.
A few hours later, further south, at Hillend, near Balclutha, crews were called to Smiths Track.
They arrived to find a farmhouse engulfed in flames. The house was soon completely destroyed, although they managed to save a garage.
The house was not occupied.
Mr Bredenbeck said the cause of the blaze remained unknown.
Last yesterday afternoon, firefighters were called to St Kilda, when a house in Oxford St became smoke-logged.
The fire was out when crews arrived, and a high-pressure fan was used to clear the smoke.
The cause of the fire was not available, but a Fenz spokesman said officers were satisfied it was not suspicious.
One person in the house was taken to Dunedin Hospital with minor injuries.
The four fires follow an incident on Sunday morning, in which an elderly Mosgiel man was found by firefighters dead in his smoking home.
On Tuesday evening, a man was found dead in a smoke-logged home in Invercargill. Police said he appeared to have died of a medical event and there were no suspicious circumstances.
