Firefighters have contained a blaze that has been burning south of Adelaide for three days.

Favourable weather during the morning helped Country Fire Service (CFS) crews in the Kyeema area to build containment lines around the fire, a tough job given the south-west flank is in difficult terrain.

There are about 100 firefighters still in the area, but aerial water bombers have been stood down.

• What you need to know about the coming heatwave
• The weather ‘double whammy’ hitting us hard
• Four confirmed dead in out-of-control-bushfires

The fire has burnt more than 90 hectares since breaking out on Tuesday, as a flare-up from a burn-off done at the start of the week.

Meanwhile in Western Australia, fire risk has been downgraded after a horror day during which four people were killed.

They have been identified as local farmer Kym Curnow, a 19-year-old woman from Germany, a 31-year-old woman from Norway and a 31-year-old man from Britain.

Smoke fills the sky in Esperance, WA on Wednesday. Photo: ABC

Country Fire Service chief officer Greg Nettleton said South Australians needed to be careful, “because we might have catastrophic fire conditions and fuel on the ground, but we won’t have a fire unless we have a spark”.

Temperatures went into the 40s for many parts of South Australia, including towns in the Riverland and places such as Port Augusta, Tarcoola and Coober Pedy.

In Adelaide, the mercury hit 37.4 degrees Celsius in the early afternoon.

The Bureau of Meteorology said there would be strong north to north-west winds ahead of a gusty southerly change for southern regions of the state late in the day.

It said there could be isolated thunderstorms but they were likely to produce little or no rain.

A water bomber flies over the scene of a bushfire at Kyeema, south of Adelaide, on Tuesday. Photo: ABC

Click the owl to see total fire bans for SA  

Some 20 fire trucks and 90 firefighters are working to control a bushfire at Yundi, about an hour south of Adelaide, after working overnight with heavy machinery and back burning to “consolidate” the fire.

Country Fire Service chief officer Greg Nettleton said crews would be blacking out hot spots and securing edges to ensure the Kyeema bushfire did not “get away”.

“Quite a large area is contained but given that area is under severe fire weather conditions today, there is still potential [for some areas] to get out.”

The fire has burnt about 86 hectares since Tuesday, with four aerial bombers, a helicopter, 172 firefighters and 42 trucks in use on Wednesday.

A CFS spokesperson said they hoped to have the bushfire contained this morning but the forecast wind change was of particular concern to firefighters.

In WA, the three young Europeans who died in the Esperance bushfires were trying to save a horse when they perished.

The three foreign nationals were working at Karranga farm, located between Grass Patch and Salmon Gums.

Farm owner Linda Campbell said the three decided to leave the farm after the man got nervous about staying and wanted to save his horse. However, the trio, hauling a horse float, turned the wrong way onto a road and ran into a wall of flames.

Local farmer Kym Curnow, 45, who also died in the blaze while trying to warn neighbours of the approaching danger, has been described as a “local legend”.