A levee has spilled over in a NSW outback town but authorities are increasingly confident floodwaters will peak below expectations.

The far-western NSW town of Menindee was forecast to hit a record flood peak on Monday of 10.7 metres, beating the 1976 record of 10.46 metres.

Readings from the Darling River have sat at 10.2 metres for the past 36 hours, raising hopes the peak may fall short of the record.

“We’re still preparing for 10.7 metres,” NSW SES’s Dave Rankine said.

“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.

About 20 residents from up to eight properties heeded the warning, with the rest remaining behind.

The floodwaters are expected to remain high for at least a fortnight after the peak as water continues to flow through the river system.

“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 46 degrees 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.

“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.

In South Australia, the Murray River hit forecast peaks with multiple flood emergency warnings at riverside towns along the waterway.

Floodwaters peaked at Berri near the SA/NSW border on New Year’s Eve and are expected to remain high for weeks.

The floodwaters are tipped to arrive in Blanchetown, west of Berri, before the weekend.

Ex-tropical cyclone Ellie continues to linger as a monsoon over Western Australia’s Kimberley region, causing heavy rainfall that could lead to flash flooding.

Dimond Gorge near Fitzroy Crossing recorded 204 millimetres in six hours on Sunday.

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.

Hail warnings for Victoria and Tasmania on Monday are no longer active but parts of west and south Gippsland have been told to brace for 90 to 100km/h wind gusts in the morning.

A total fire ban was issued for the Mallee region in Victoria’s north-west on Monday.

Melbourne was tipped to reach a maximum of 31 degrees before conditions cooled, while Hobart was forecast to hit 28 degrees after the state’s three-day heatwave warning ended.

A low-intensity heatwave will begin across Queensland’s south on Monday and is forecast to remain until Wednesday.

-AAP