South Australians are being urged to prepare ahead of extreme fire danger conditions on Monday.

Both the eastern Eyre Peninsula and Mount Lofty Ranges have been declared extreme fire danger areas by the Bureau of Meteorology and Country Fire Service (CFS), while high ratings span the rest of the state, with only the Adelaide metropolitan area falling into a moderate risk.

Temperatures are set to reach 38 degrees Celsius in Adelaide, 41C in Port Augusta, 40C in Port Pirie, 38C in Mount Gambier and 37C in Whyalla.

Premier Peter Malinauskas called on people to be ready for any potential issues.

"Complacency is the ultimate enemy when it comes to bushfire risk," he said.

"If people throughout the state are genuinely well-prepared and planned, that could literally be the difference between life and death."

At least four SA regions are expected to be declared extreme fire danger areas on Monday, with emergency services on high alert. (ABC News: Che Chorley)

CFS chief officer Brett Loughlin said a combination of hot, windy and dry conditions would be at play, and it was essential for households to prepare their bushfire action plans.

"I urge people to take the risk seriously," he said.

"We still have a lot of summer to go, and it's only going to continue to be dry, and these risky days are only going to continue to occur."

Parklands fires under investigation

Meanwhile, police are investigating a series of suspicious fires that broke out in Adelaide's parklands on Saturday.

Firefighters were called to Veale Gardens in the South Parklands just after midday following reports of smoke, and a small grass fire was extinguished.

Police are investigating a series of suspicious fires in Adelaide's parklands. (ABC News: Che Chorley)

Authorities responded to another incident at around 7pm near Sir Lewis Cohen Avenue, extinguishing four separate fires believed to be deliberately lit.

Another grass fire was reported just before 11pm near West Terrace.

Police say the area was searched with air assistance, but no suspects were located.

Mr Malinauskas said those involved faced the possibility of "very severe punishment".

"Pull your head in," he said.

"We live in the driest state, in the driest continent, anywhere in the world.

"This is not the time of the year to be taking any risks."