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.