More heavy rainfall is forecast for the outback, cutting roads across South Australia's north-east, including the Barrier Highway.
The Bureau of Meteorology has forecast up to 100 millimetres of rain in parts of the Flinders Ranges, the southern part of South Australia's north-east pastoral district and the Riverland, along with the far west and lower west of NSW.
South Australia Police has closed the Barrier Highway ? which links Adelaide with Broken Hill and western NSW ? due to significant flooding over the road.
The closure has quashed many traveller's plans to make the most of the recently opened South Australian border.
Authorities have urged motorists hoping to travel to and from South Australia to take extra care on the road, as more rain is expected over the coming days.
More than 100mm of rain fell in some parts of far west NSW overnight.
Bob Pearce from Sunnydale Station, 50 kilometres south of Broken Hill, said the last time he could remember a downpour like this was in the 1990s.
He said his family had worked Sunnydale for more than 100 years and a rain event like last night's was extraordinary.
"We've seen a lot of highs and lows and we've had it that dry for that long, you know, we couldn't get wet if we fell out of a boat," he said.
"Certainly last night, you know when it rains it pours."
Mr Pearce said the downpour couldn't have been better timed, with the station purchasing sheep this week.
"We've got 900 coming probably towards the end next week, so they'll have to be fitted with snorkels and flippers, but perfect timing as far as sheep goes," Mr Pearce said.
Silverton resident Helen Murray measured more than 50mm throughout November, including 18mm yesterday.
She said it was a welcome surprise to wake up to.
"Laying in bed at 3 o'clock this morning and all of a sudden it was just bucketing down," she said.
"It woke me up; it was thunderous on the roof, it rained for a little while and I thought this was nice."
"Then around 5-ish it started again, equally as heavy and went for probably half an hour to an hour, and next thing we've got creeks running and there's water everywhere out here."
A flood watch remains in place for South Australia's Flinders Ranges and parts of the North East Pastoral Districts.
© ABC 2021
13:12 AEDT Goondiwindi's 65-year-old levee has once again saved homes from major flooding, but the town is now surrounded by water and there are fears some rural communities could cut off for days, if not weeks.