Six buildings have been destroyed by a bushfire in South Australia's Fleurieu Peninsula despite crews stopping the spread of the dangerous blaze, the Country Fire Service (CFS) says.

Damage assessment teams have confirmed four sheds, an outhouse and a greenhouse have been destroyed in Thursday's fire at Mosquito Hill.

The total area burnt is estimated to be about 310 hectares while the total damage bill remains unknown.

A watch and act message remains in effect for Mosquito Hill and Tooperang.

The fire blackened several dozen hectares of scrub and farmland at Mosquito Hill after it was whipped up in high temperatures and strong winds.

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The fire's forward advance had been slowed, the CFS said, but it was still out of control and burning in patches within the fire's edge.

Conditions were continually changing, the service added.

Crews are now monitoring smouldering logs and haystacks and some will be there through the night.

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The fire had been heading in a north-easterly direction for Mosquito Hill and Tooperang and threatening homes in the Kokoda Hill area.

Locals have described a lucky escape from serious property damage and destruction on a day where the fire danger was considered extreme.

"A lot of luck," local farmer and firefighter Ollie Fehrmann said.

"Because in this country it's really hard to fight the fires because you've got to wait for them to come across the hills and through the scrub so it's very lucky."

Acting CFS deputy chief officer Brenton Eden said while the area concerned was not heavily populated, the fire was still out of control.

He said although no homes had been lost, some abandoned buildings had been destroyed.

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"What we are noticing through from a community point of view is we are being overwhelmed with calls both here and in Adelaide fire for people reporting smoke from as far north as places like Harrowgate and probably as far east as Murray Bridge.

"Whilst we appreciate people calling the emergency services for smoke sightings, please be aware that most of that smoke is coming from the Mosquito Hill fire, so we're entering into an evening now with cooler temperatures and lighter wind speeds.

"[That will have] much greater impact with our aerial and ground resources so I would expect on each of the subsequent reports for this evening that the prognosis for the fire will considerably improve."

However, Mr Eden said people living to the east of Mosquito Hill, around the Scott Conservation Park area, still needed to be very aware that they had a fire moving in their direction.

"People need to be enabling their bushfire survival plans and if their property is not defendable then they should be leaving and leaving away from the fire."

The Goolwa to Mount Compass Road and Deep Creek Road have both been closed.

People are urged to take shelter and only leave if the path is clear to reach a safe place.

The Bureau of Meteorology said that a weak southerly change would be moving through the area this evening.

A spokesman said that winds of 20 to 30 kilometres per hour were expected through the night, increasing to speeds of between 30 and 40 kilometres on Friday morning.

Total fire bans will apply in the Northwest Pastoral and West Coast districts today, where severe fire danger conditions are expected.

An aerial photograph of the Mosquito Hill fire taken by CFS Air Observers. ( Supplied: CFS )

Bushfire near Mosquito Hill on December 31, 2015. ( Twitter: @claireryan91 )