Threat level lowered on SA bushfire

A bushfire in South Australia is close to being contained, with the threat level downgraded after the blaze destroyed grape vines in Clare Valley.

Some vineyards in South Australia's Clare Valley have been destroyed but fire crews are close to containing a blaze burning in the state's mid-north.

The fire posed a risk to lives and property in the area at one stage on Tuesday but the Country Fire Service downgraded the alert level late in the day to a simple advice message.

A CFS spokesman said the blaze had destroyed about 242 hectares and continued to burn in a number of small pockets.

About 180 fire fighters were deployed to the area, backed by aerial support. The blaze resulted from a out-of-control prescribed burn.

While some grape vines had been lost, there were no reports of any loss of property.

Fire crews were expected to remain on the scene for the next 24 hours to guard against any flare-ups.

The fire came amid unseasonally hot conditions across SA with temperatures in Adelaide pushing into the low 30s and even higher in some regional centres.

The CFS also declared severe risk conditions for the Mt Lofty Ranges and mid-north on Wednesday.

The Bureau of Meteorology said cooler conditions were expected on Wednesday and Thursday with possible showers.

But the warmer weather was forecast to return for the start of the Easter weekend, with Adelaide tipped to have tops of 31C on both Good Friday and Easter Saturday.

"Everyone wants to have a restful Easter long weekend, including our volunteer firefighters," CFS state duty commander Yvette Dowling said.

"So people need to be aware of where they may be travelling to, and what the conditions and fire restrictions may be in the area.

"One small spark could quickly become a very large fire under the conditions we are expecting."