Catastrophic bushfire conditions have been declared for South Australia's mid-north on Friday with authorities warning some properties could be impossible to defend.
Another five SA districts will experience extreme conditions and three will be severe.
A combination of heat, strong winds and dry lightning has prompted the Country Fire Service to put all crews on standby along with its full complement of firefighting aircraft.
"In some areas of the state conditions will be that bad it will be possible that it's not safe to stay and defend," CFS duty commander Nick Stanley said.
"If you have a bushfire survival plan and your plan is to leave, make those arrangements now rather than leave it to the last minute when it could potentially be too late and your life could be put at risk."
Up to 13 parks and reserves across SA's mid-north will be closed on Friday and people planning to travel through the area have been urged to postpone their plans for 24 hours.
Winds have been forecast to reach around 50km/h and are expected to change as two troughs move across the state.
Conditions across SA were also severe to extreme on Thursday but the state escaped largely unscathed.
The most serious incident came in the mid-north where a fatal crash at Hope Gap sparked a grass fire that was quickly brought under control.
Grass fires were also burning in the far north at Amata and Murputja but posed no threat to lives or property.
Across Adelaide, the Metropolitan Fire Service battled five house fires within a 12-hour period, including two thought to be deliberately lit.
Commander Stanley said it was not particularly unusual to experience catastrophic conditions in SA in December but Friday's combination of heat, winds and lightning could result in a challenging day for firefighters.
