Flood levels are holding steady at a town in the NSW outback, with authorities increasingly confident they will peak below a 47-year record.
A flood peak of up to 10.7 metres was tipped to hit the far-western NSW town of Menindee on Monday, surpassing the 1976 record of 10.46 metres.
But the Bureau of Meteorology has since revised its forecast, declaring further rises to 10.7m are possible from and around Thursday.
"The situation is being closely monitored and predictions will be revised as required," its latest alert reads.
Readings at Menindee show the Darling River remains steady at 10.2m, raising hopes the peak may fall short of the record.
"We're still preparing for 10.7m," NSW SES's Dave Rankine told AAP.
"But with no more water planning to be released by Water NSW in the next 24 to 48 hours, it's hard to see how that river height will go up any further."
Locals from 31 properties around Menindee were advised to evacuate before New Year's Eve, with residents from seven or eight heeding the warning.
River levels are expected to remain high (around the 10m mark) for at least another fortnight as water continues to flow through the river system, the BOM said.
"These are very slow-moving flood events," Mr Rankine said.
"The floodwater that we're seeing now in Menindee fell in Tamworth in September and Moree in early October, so there is quite a long transition."
A private levee near a river bank was breached overnight, stranding 80 sheep and several calves in a paddock for hours before being rescued.
Main levees around the town have been shored up with earth and sandbags, although efforts were hindered by extreme heat as the mercury reached 46C on Sunday.
Pre-prepared sandbags are being shipped in from the Murray River to lighten the load for locals and about 20 emergency services workers on the ground, along with automatic machines.
Menindee Regional Tourist Association president Rob Gregory said the community could still use a few more bodies to help.
"We're probably a little bit under-resourced at the moment, in regards to feed on the ground to help shifting sandbags and that sort of thing," he told ABC TV.
The BOM has also issued a severe thunderstorm warning with heavy rainfall, large hailstones and damaging winds expected in the west and south-east of the state for late Monday.
In South Australia, the Murray River hit forecast peaks amid multiple flood emergency warnings at riverside towns along the waterway.
Ex-tropical cyclone Ellie continues to linger as a monsoon over Western Australia's Kimberley region, causing heavy rainfall that could lead to flooding.
Major flooding was expected to develop at Fitzroy Crossing, about 400km east of Broome, from Monday afternoon after 353 millimetres of rain fell upstream at Dimond Gorge in the 24 hours to 10am.
Rainfall totals of 100mm to 200mm are tipped to drench the area during Monday into Tuesday, with some communities already isolated as roads are rendered impassable.
The Northern Territory's northern regions of Daly and Tiwi, as well as parts of the Arnhem and Gregory districts, are also in the firing line as residents prepare for damaging winds and surf.
Thunderstorm warnings for Victoria and Tasmania on Monday have been cancelled but a total fire ban has been issued for the Mallee region in Victoria's northwest.
Australian Associated Press