SA's west braces for severe thunderstorms

"Severe thunderstorms are likely to produce heavy rainfall that may lead to flash flooding in the warning area over the next several hours," the SES said in a statement.

Meanwhile, a watch and act alert for severe thunderstorms with wind gusts of more than 90km/h and intense rainfall with dangerous flash floods for the West Coast, Yorke Peninsula, Kangaroo Island and North East Pastoral districts has been cancelled.

The Yorke Peninsula town of Kadina recorded 83mm of rain in the four hours to 1pm on Sunday, its wettest day on record.

The SES warned the danger may not have passed for the West Coast, Yorke Peninsula, Kangaroo Island and North East Pastoral districts.

"Severe thunderstorms may redevelop later today and the situation is being monitored," the agency said.

The Bureau of Meteorology has also issued an alert for possible "widespread floods" for 14 catchments and regions after up 120mm of rain in fell in some areas the 24 hours to 9am.

Another 30-80mm of rain is likely to fall with isolated higher falls up to 120mm possibly isolating some communities, the forecaster said, in the 48 hours to midnight on Monday.

The SES crews have rescued at least 11 people near Coober Pedy with the floodwaters cutting off remote communities and washing away part of the Olympic Dam Hwy destroyed between Woomera and Roxby Downs.

Local roadhouses, pubs and caravan parks posted photos of ochre-coloured floodwaters flowing over part of the bitumen highway that had sunk about two metres.

Roxby Council said the SA Department for Infrastructure and Transport was trying to reopen a lane of the highway by late Sunday afternoon.

"A significant portion of the road was washed away in yesterday's heavy rains," the council said in a Facebook post.

"Road blocks are currently in place at Roxby Downs and Port Augusta.

"Motorists are advised to delay their travel plans to or from the region if possible."