A total fire ban has been declared for South Australia on Tuesday ahead of catastrophic conditions expected on Wednesday.

Key points: Total fire bans have been declared across SA for Tuesday and Wednesday

Total fire bans have been declared across SA for Tuesday and Wednesday Catastrophic conditions are expected in the state's central districts on Wednesday

Catastrophic conditions are expected in the state's central districts on Wednesday Record and near-record November temperatures are forecast for Wednesday across the state

It is one of the first times the Country Fire Service (CFS) has declared a pre-emptive fire ban 24 hours before a hot and windy day, the agency's head said.

"It's pretty unusual that we take a precautionary fire ban and I hope that people will realise we've done so in response to the severity of the conditions which are forecasted for Wednesday," CFS chief officer Mark Jones said.

"We ask people not to undertake acts which are risky, to be vigilant, to take care, and I'd reiterate the message to have a plan."

Catastrophic fire conditions are expected on Wednesday for the lower Eyre Peninsula, the Yorke Peninsula, the Mid North and the Mount Lofty Ranges, when a total fire ban will also be in place.

All other regions have severe or extreme ratings, including the Adelaide metropolitan area.

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The Bureau of Meteorology has forecast a top of 42 degrees Celsius for Adelaide on Wednesday, after a high of 29C on Tuesday.

The record November temperature for Adelaide's West Terrace weather station is 42.7C, set in 1962.

Record temperatures are predicted in some country areas.

The bureau's acting SA supervising meteorologist, Paul Lainio, said wind speeds would reach 50–60 kilometres per hour in western and southern parts of South Australia on Wednesday.

"So [there are] extra dangerous conditions developing during Wednesday and people need to take care," Mr Lainio said.

Metropolitan Fire Service chief officer Michael Morgan urged people to leave their properties ahead of dangerous fire conditions if they were unprepared.

He said firefighters' lives would not be put at risk.

"The important message for everyone is to be prepared and understand the risks that will be presented on Wednesday," Mr Morgan said.

A cool change is expected to come through Adelaide between midnight and early morning on Thursday.

Fire season already started in SA

The fire danger season has officially started in all of South Australia's fire ban districts, apart from the lower South-East, where the season starts on Friday.

Two houses and six sheds were destroyed in a fire at Duck Ponds near Port Lincoln last week.

The CFS said two people, including one firefighter, were treated for minor injuries.

Eight fixed-wing water bombers battled gusts of up to 90kph.

The SA Government says a new app to warn residents of fire danger will be online next month. ( ABC News: David Frearson )

The State Government scrapped an app that provided information about ongoing bushfires and fire bans in January last year after it collapsed under heavy load during catastrophic fire conditions.

It ordered a new version of the Alert SA app soon after, originally saying it would be ready for the 2018–2019 fire season.

Emergency Services Minister Corey Wingard on Monday said the app would now be ready by "early December".

"The product that had been in development reached the user-testing phase but at that point failed to meet our expectations," Mr Wingard said.

"We have gone down another path with a different vendor. The new app is based on the NSW RFS Fires Near Me app.

"The new app is based on a reliable and stable product and we look forward to having it come online."

The CFS instead urged people to seek information from multiple services, including its website cfs.sa.gov.au.