Homes and lives are under threat at two locations around Adelaide with emergency warnings issued for fires in the Adelaide Hills and at Angle Vale, in the city’s north.
The Country Fire Service says 36 fire trucks and eight aircraft are battling the fire which started at Cudlee Creek amid catastrophic weather conditions.
It continues to burn out of control in grassland and is threatening the towns of Lobethal and Lenswood.
Another 20 fire trucks are fighting the Angle Vale fire which is also burning uncontrolled in grassland.
The fire is burning towards homes at suburban Munno Para Downs.
In both cases, the CFS says crews are unable to stop the fires from spreading.
They come as SA is experiencing its worst day for fire conditions so far this summer with catastrophic risk declared in six districts.
The state is being hit on Friday by a combination of extremely high temperatures and rising winds with the potential for thousands of lightning strikes in the afternoon.
A gusty wind shift during the day will cause added dramas with the Country Fire Service warning that if fires start, they will be almost impossible to contain.
“Under these conditions, they will be so erratic and move so fast and develop so quickly it doesn’t matter how many firefighters, we’re not going to stop the forward spread of these fires,” Deputy Chief Officer Andrew Stark said.
“These are certainly the most dangerous conditions we’ve faced this season.”
Temperatures in some parts of the state are expected to get close to 50C with Adelaide forecast to have a top of 46C which would make it the city’s hottest ever December day.
The mercury had already reached 43.1C in the city by 11am after an overnight low of 33.6C.
Rising winds on the Yorke Peninsula also whipped up dust with police warning that visibility was low.