Rivers rise with storm water in the town of Gawler, South Australia. Picture: AAP Image/David Mariuz

Heavy rainfall is expected to batter the state again tomorrow and won’t ease until about lunchtime on Tuesday.

Bureau of Meteorology senior forecaster Vince Rowlands said the outlook for the rest of the weekend was bleak.

“We do have another frontal system moving from the west tomorrow and we will be heading into another period of wet weather,” he said.

More rain could be concerning for Adelaide, according to Mr Rowlands, because of the weather it copped earlier in the week.

Flooding in the town of Tanunda, the Barossa Valley, South Australia, after heavy rainfall. Picture: AAP Image/David MariuzSource:AAP

Up to 100mm of rain is predicted over the ranges in South Australia between Sunday and Tuesday and Adelaide could be hit with up to 40mm.

A flood emergency warning is in place for residents in Port Wakefield, north of Adelaide.

Major flooding from the Wakefield River is already occurring and water levels are continually rising, the SES said on Saturday.

Authorities say residents who have not prepared for flooding should leave, but only if it is safe to do so.

Residents watch rivers rise with storm water in the town of Gawler, South Australia. Picture: AAP Image/David MariuzSource:AAP

Families who have prepared their homes for flooding should move valuables to a safe place.

Traffic has been diverted around Port Wakefield and between Virginia and Two Wells.

The SES said flooding was occurring in Gawler, north of Adelaide, and surrounding areas and may threaten people’s safety.

Suburbs which may be impacted include Gawler, Hillier, Gawler River, Angle Vale, Penfield Gardens, Two Wells, Lewiston, Virginia, Port Gawler and Buckland Park..

There is a possibility that flooding may worsen if the river at Gawler breaks its banks or levees fail.

Flooding southeast of Adelaide is stabilising but authorities warn people threats may still be present as reports of damages to 20 structures emerge.

An extra 60,000 sandbags are expected to be flown into South Australia and will be distributed across the state for collection and about 100 members of the Australian Defence Force are helping with the ongoing sandbagging efforts.

Premier Jay Weatherill said about 20 structures around the town of Balaclava had been impacted, but authorities weren’t sure if they were houses. Homes had been flooded at Old Noarlunga as well.

“There’s no doubt there are people that have been affected,” he said.

The government doesn’t know how many homes and business have been affected.

“I think we are talking in the dozens at the moment,” Mr Weatherill said.

“It’s hard for us to get into these communities at the moment and we are still getting patchy information.”

He then thanked the emergency services workers who had been kept busy across the state, and said they would be relieved by interstate colleagues over the coming days.

“Extraordinary effort ... the care, the professionalism, the capability and the energy they have shown has been nothing short of extraordinary,” he said on Saturday.

“It has kept our community safe.”

The deep low pressure system which caused the havoc has moved away from Adelaide and while flooding is stabilising around the Angas and Bremer catchments, the SES is advising people to remain vigilant.

The SES is also reminding residents not to walk, ride or drive through floodwater, or allow children to play in or near floodwater.