The town of Lyndoch, northeast of Adelaide, has been flooded overnight, after the town's creek burst its banks.

The SES issued a flood emergency warning after water levels continued to rise.

9NEWS Adelaide will air a special storm bulletin at 8.30am (ACST). Live stream it here.

Two people were rescued from cars and residents urged to leave their properties.

About 60km further north, another emergency warning was activated for towns along the Gilbert River.

"Locations which are impacted include Saddleworth, Tarlee, Manoora, Stockport and Riverton," the SES said in a statement.

Wind gusts of up to 115km/h were recorded at Ceduna just after midnight, and at Cummins at 3am.

A gale warning is in place for the Upper South East Coast, while a strong wind warning exists for Adelaide Metropolitan Waters, Lower West Coast, Central Coast, South Central Coast, Spencer Gulf, Gulf St Vincent, Investigator Strait and Lower South East Coast.

A number of flood warnings are also still in place, however a severe weather warning for the state has now been cancelled.

For a full list of SA weather warnings, visit the BoM website .

Premier Jay Weatherill is expected to visit the state's mid-north today to see the damage caused to the region's electricity infrastructure and speak with locals affected most by Wednesday's big blackout.

Mr Weatherill described the storm as "catastrophic" and said it had involved weather events not seen before in South Australia, "such as twin tornadoes, which ripped through the northern parts of our state".

The intense low pressure system was packing winds of up to 140km/h, among the strongest the city has experienced, prompting an unprecedented warning from police for workers to head home early and stay home amid concerns emergency services might not be able to cope.

Several public schools in regional areas will remain closed, as well as school bus routes in Balaklava, Port Pirie buses, Napperby Primary School Buses and Kadina, Ardrossan and Clare buses.

Meantime, tens of thousands of homes across South Australia were still without power well into the night, despite restoration to much of Adelaide and metropolitan surrounds.

The Marne river near Cambrai. (Supplied: Jody Miltenoff) ()

More than 7000 homes were hit with more outages again yesterday afternoon.

Aberfoyle Park, Kiana, Mount Hope, Sheringa, Melrose, Foul Bay and Flagstaff Hill were among several suburbs where power was out, which SA Power Network has attributed to “storm activity”.

Transmission company ElectraNet said most services had been restored and it hoped to have one of the transmission lines repaired by Sunday, using temporary towers from interstate.

The company also backed assertions from the premier that no energy system in the world could have survived such an event without going down.

The State Emergency Service has responded to more than 600 calls for help.

The State Emergency Service advises that people should:

Move vehicles under cover or away from trees;



Secure or put away loose items around your property.



Keep clear of fallen power lines;



Don't drive, ride or walk through flood water;



Stay indoors, away from windows, while conditions are severe.

You can contact SA SES on 132 500 for help. For life-threatening emergencies contact 000.</s>South Australians are preparing for one of the most extreme weather systems to hit the state in decades, bringing drenching rain and damaging winds.

Up to 100mm of rain is forecast for the Adelaide Hills, with the storm expected to hit at about midday on Wednesday. Winds should average 90km/h, whipping up ocean waves to more than 10 metres, but gusts are forecast to be much stronger.

The State Emergency Service says 43,000 sandbags have been distributed and more are to be handed out on Wednesday. SA Power Networks says there will probably be power outages and some could be long.

State cabinet’s emergency management council was also meeting to consider what action would be required as the storm hit and during the cleanup.

The Bureau of Meteorology has issued a severe weather warning for the state’s west coast and large parts of the Eyre peninsula and that warning was expected to move east during the day. A flood watch was also in place for the Adelaide Hills.

“This depth of the low, this close to the coast, is very damaging,” said the Bureau of Metereology SA’s director, John Nairn. “It’s a very significant event for South Australia. It’s very rare.”

Nairn said records suggested SA had not experienced a storm so severe for more than 50 years.
The state of South Australia suffers widespread blackouts triggered by severe weather conditions.