• Record rains fell in areas of the Northern Territory, South Australia and Western Australia.

• Canberra was flooded as the normal rainfall for all of March fell on the capital in just 24 hours.

Outback areas which two days ago were sweltering in temperatures in the 40s and swept-by duststorms were left deep under swirling floodwaters as the storms dumped sheets of blinding rain.

Broken Hill was swamped in what residents say is the worst flooding since 1932. A car was washed down a swollen creek, thousands of sheep are feared lost, roads and railway lines were cut, and emergency services were preparing to drop food to stranded householders and travellers.

Forty people and their vehicles were stranded for several hours on the Barrier Highway at K Tank, about 25 kilometres east of Broken Hill, as the normally dry creek became a raging watercourse.

The vehicles were towed through the flooded creek, and Broken Hill police said last night the people were all safe. But interstate truck drivers were still stranded along the Barrier Highway, and graziers were unable to move from homesteads surrounded by water.

Mr Don Campbell, chief pilot for the Royal Flying Doctor Service at Broken Hill, said a meeting to assess the situation would be held this morning with State Emergency Services personnel and the police.

Torrential rain has been falling since the weekend in a 1,000-kilometre arc stretching from the Simpson Desert into the western reaches of NSW.

One station on the edge of SA's Flinders Ranges recorded the State's highest rainfall in 24 hours - 273 millimetres (nearly 11 inches).

The normally dry Wilpena Creek in the same area was turned into a river 19 km (12 miles) wide overnight as it raged out of the ranges into parched saltbush country around Lake Frome.

A monsoon swept into SA from the Kimberley region, flooding the opal-mining town of Andamooka and dumping huge downpours on stations in the Flinders Ranges before moving on to Broken Hill.

Broken Hill's reservoirs were almost overflowing after an intake of up to 8,000 megalitres, or a year's supply, in less than two days.

The first falls brought joy to the area, which had endured 50 days without rain and was under tight water  restrictions. But then the downfall became a torrent.

In Canberra, police warned children to keep away from swirling stormwater drains throughout the city, and flooding closed several roads.

The Canberra weather bureau said 61 mm of rain fell between Monday night and 3 pm yesterday, with 44 mm between 9 am and 3 pm. The city's average for March is 58 mm.

The Barrier Highway from Adelaide to eastern NSW was cut at three points, and the Silver City Highway was also cut.

Heavy rain was continuing last night, and the weather bureau said no let-up was expected until this afternoon as the depression heads slowly towards the east coast.

'It's like an ocean going accross the road'

Outback people told vivid stories yesterday of the storms which have swept swept across the centre of Australia since Monday.

Mr Lambert Hannessen, licensee of the Bordergate Hotel at Cockburn, on the NSW-South Australia border, said he had been receiving two-way radio reports from stations and stranded truck drivers.

"Five miles west of here it's like an oceaa going across the road," he said. "If the banks break at O'Lary, Wompinie Station will go.

"The property is pretty well flooded now. There's a bloke on it with his caravan tied to a tree. His diesel task is moving. He has water right up to the house.

"We have people in the pub now, just trying to keep them dry. The fellow bringing our meat supplies from Adelaide got stuck aboot 173 kilometres south of here at Yantha.

"My wife is cooking up soups."

Mr Geoff Woods, regional livestock officer for the NSW Department of Agriculture at Broken Hill, said some sheep were able to get on higher ground in the Brokea Hill district as water swept across the low-lving areas.

But the sudden cold snap was killing freshly-shorn sheep.

Mr John Lawrence, grazier of Nine Mile Station, Broken Hill, said: "We sheared 525 weaners recently - and they are all dead bar one or two which we are trying to keep alive, but there is not much we can do.

"We are very worried about 1,900 weaners we sheared last week.

"We won't know till we are able to get out and check them what the damage is.

"I have a total of 9,000 sheep and we have now sheared about 6,000 of them. We don't know how many we have lost."

Mr Wally Freeman, retired fruit fly inspector, of Cockburn, who often spends a little time in the town's two hotels, one on each side of the NSW-SA border, as well as in community work, became a flood casualty yesterday.

When the rains came, he went to switch on the power at the town's reservoir so that fresh water — rationed because of drought conditions — could flow freely again.

But he slipped and fell while in the act, broke a rib, and last night was stranded in Cockburn, unable to see a doctor.

At Motpena Station on the western edge of the Flinders Ranges, where South Australia's highest 24-hour fall was recorded, manager Malcolm Johnson and his wife Dulcie built a sandbank to keep floodwaters out of the homestead.

"What was a bit of a gutter out the front of the place is now a roaring creek with foot-high waves on it," he said.

"It's 200 metres wide today but it hasn't run with anything in it since 1898," he said.

"This has been something I don't think white man's ever seen before.

"All our creeks on both side of the ranges have breached the limits anybody's seen before and there's still all that water to come down out of the hills."

At Arkaba Station, in the Flinders, Mr Dean Rasheed said a fall of 218 millimetres had eclipsed a 1916 record.

The city of Broken Hill has had all roads into it cut off since early Monday morning.

The beneficiaries have been the hotels and motels.

They are jammed with salesmen, tourists and out-of-town St Patrick's Day revellers who have been trapped since the flooding began.

The region had been subjected to a 50-day drought until this week and water had been rationed to alternate days.

Now both of the town's reservoirs are filled to overflowing.

Mrs Irene Sweet said she had not seen rain like it for 30 years - "driving through Broken Hill, every intersection you come to is full of water."

For Mr Dale Dwyer, 26, the floods mean that his wedding day on Saturday will probably have to be postponed.

"It's bloody horrible," he said. "I have a groomsman and flowers coming up from Adelaide. I have an MC coming from Roxby Downs and nobody can get through."