AN UNCONTROLLED bushfire fire is burning in South Australia's mid-north with total fire bans declared for most of the state.

The CFS says the fire at Bundaleer North, near Wehrmann Road, Humphris Road, Burnside Road and Springs Road, may threaten property and the safety of people.

The fire has burnt through more than 1000ha of pine forest and grazing land.

The CFS is hoping to contain the blaze before the weather worsens.

Temperatures in the 40Cs and strong northerly winds have been forecast for most parts of the state.

The Bureau of Meteorology said Adelaide would have a top of 42C with north-easterly winds to 35km/h ahead of cooler change set sweep across the city late in the day.

In the Riverland the mercury was expected to hit 44C at Renmark while Ceduna, on the west coast, was forecast to have 45C along with Wudinna, on Eyre Peninsula.

The Country Fire Service listed the bushfire risk as extreme in six districts and severe in the remaining seven.

Police said operation Nomad patrols will be out in force today to check suspicious activity in high-risk areas and keep tabs on known firebugs.

If the mercury reaches 40C it will be Adelaide's fifth day above that mark so far this summer.

Tomorrow the bureau has forecast some light morning showers for the city with a more comfortable top of 26C.