Firefighting efforts in South Australia will be made easier by reduced temperatures forecast for today.

Emergency services have been working through the night to ensure two fires at Kingston and Port Lincoln do not jump containment lines.

Yesterday the Port Lincoln blaze, on South Australia's Lower Eyre Peninsula, destroyed 12 houses and nine sheds and several firefighters suffered smoke inhalation.

Power has now been restored to most of the 6,000 homes that were affected by the blaze.

Region Commander Kevin May says residents are now returning to the area but are advised to take care.

"Some people were moved to a safer area today on advice from the police department but most of those who have lived in the area that have had the fire impinging on them have been allowed to go back home so they can check on their own premises," he said.

Port Lincoln Mayor Peter Davis says there have been no reports of deaths but he is concerned.

"I shouldn't be surprised if there's been loss of life, particularly when it ignited ... that was an explosive situation around three or four hours ago," he said.

Mr Davis says there has been significant property loss but conditions have eased.

"Clearly there are still hotspots but because the wind speed is below 10 knots it's moderated enormously," he said.

'Fleeing for our lives'

At the height of the drama, residents fled Port Lincoln as thick smoke blanketed much of the town.

Port Lincoln resident Ray said he thought his house was among those destroyed.

"I was probably driving out my driveway with flames above the roof of the house at the backdoor," he said.

"I'd just like to say to people who are out there on the roads and blocking the roads, people like me are fleeing for our lives you know."

About 4,000 homes in the area are still without power.

Port Lincoln resident Michael Sleep, who sent photos of the blaze to ABC Online, said the situation in town had been "pretty scary".

"Wind changed direction and there was smoke everywhere with ash blowing in. Had to get on the roof and block and fill the gutters," he said.

CFS spokeswoman Hayley Cahalan said 150 firefighters and 30 fire trucks were used to contain the blaze, as well as water bombing aircraft.

Kingston blaze

Ms Cahalan said fire crews would be back-burning through the night at Kingston to bring the fire there under control.

She said smoke would make travelling in the area dangerous.

Belinda Gibson from the weather bureau said the temperature had eased to about 33 degrees in Port Lincoln.

She said conditions should continue to ease overnight.

"Now that the change has come through Port Lincoln has cooled down. Down at Kingston I imagine it's probably cooled down a little bit," she said.

"The winds should start to be easing back through the evening, increasing humidity and lowering the temperature."

Rob Sandford from the CFS said sightseers had been a problem in bushfire zones through the day.

"Our message all day today has been for people not to enter the area and not try and leave the area where these fires are because it is just too dangerous," he said.

"They are putting themselves and the emergency services and the rest of the community at risk."

More than half of South Australia's 15 fire ban districts have been subject to catastrophic fire danger ratings today, due to hot and windy weather.