Looming heatwave prompts blackout warning

South Australians have been warned about potential power black outs as the temperature soars over the next three days.

The mercury is expected to reach 37 degrees in Adelaide today, before highs of 41 degrees both tomorrow and Friday.

The state's Energy Minister Tom Koutsantonis has told 9NEWS diesel generators will be placed on standby in case power supplies run short.

“We will, of course, monitor the situation and be ready to use our new ministerial powers of direction over the market or our state-owned power plant if required,” he said.

“That is considered very unlikely at this stage. We launched our energy plan to boost local power supply and improve grid security, and importantly, the independent market operator has said that our plan has put SA in a good position this summer.

”The Australian Energy Market Operator has issued a "lack of reserve" notice for between 5.30pm and 6pm tomorrow.

It says the contingency capacity reserve required is 600 megawatts, but the minimum reserve available is 575 megawatts.

The State Government has come under fire over its management of the state's energy system since a statewide power blackout in September of 2016.

It is likely to be a key issue when SA voters head to the polls in just three months time.