Dangerous fire warning for SA

Conditions similar to those during South Australia's deadly Pinery fire have been predicted across much of the state, putting emergency services on high alert.

Hot and windy conditions have been forecast on Wednesday with the fire risk in at least four districts expected to be extreme.

In about eight other districts the risk will be severe.

Bureau of Meteorology acting regional director John Nairn said a major concern was an expected wind shift around midday as a cooler change pushed through.

Areas most at risk include the mid-north, the Mount Lofty Ranges and the upper and lower southeast.

"So those are rather dangerous conditions for those zones in particular," Mr Nairn told reporters on Tuesday.

Thunderstorms will also pose a risk but could eventually bring some much-needed rain with falls of up to 20mm in the north and about 5mm further south.

Country Fire Service state co-ordinator Mark Thomason said all firefighting aircraft would be on standby.

He said the conditions would be similar to those experienced in November when the fire at Pinery was fanned by shifting winds and eventually destroyed about 80,000 hectares of crops and grassland, claimed two lives and destroyed hundreds of buildings.

"During the Pinery fire we saw that wind change come in and the flank of the fire became the front," he said.

"That's our concern. We don't want people on the roads to assume that the fire is just travelling in one direction and it's not going to change."

Also on Tuesday the bureau issued a severe thunderstorm warning for western parts of SA.

It said damaging winds of up to 90km/h were possible with centres to be affected including Ernabella, Maralinga, Oak Valley, Cook and Nullarbor.