Thousands of NSW residents are bracing for flash flooding with heavy rain and thunderstorms to hit many parts of the state.
Ninety-eight flood warnings are current, with the SES performing 21 rescues and answering hundreds of calls for assistance overnight.
The focus of the crisis continues to be in the state's far northeast and southeast, close to the Victorian border.
Communities in towns under threat from flooding in northern parts of the state will soon begin to experience the worst of the disaster.
NSW emergency services in for busy weekend
NSW Emergency Services Minister Steph Cooke said large parts of the state, including the inland and west, were in for a "difficult few days".
Emergency services are preparing for a busy weekend as the wild weather arrives, with volunteers handing out 30,000 sandbags a day.
"We are quite literally sandbagging the state," Ms Cooke said on Saturday.
SES Commissioner Carlene York said flash flooding and hail could be made worse by heavy winds which could easily uproot trees in saturated areas.
"It's already extremely busy and we're expecting this next 24 to 48 hours to see more requests for assistance," she said.
In the north, emergency warnings are in place for Moree, Narrabri and the hamlet of Terry Hie Hie, while an evacuation order is current for Moama in the southern borderlands.
The Bureau of Meteorology warns the big wet will likely continue, with widespread showers and thunderstorms forecast for eastern NSW, including Sydney, resulting in flash flooding for many regions.
The bureau says the northeast is an area of concern as a trough and possible low-pressure system develops off the coast, bringing heavy rain to the Northern Rivers, including Lismore and Byron Bay.
Two hundred defence personnel are being deployed in Dubbo, Moree and the Northern Rivers, with two more Australian Defence Force helicopters coming online ready for night rescues.
Specialist swift-water rescue crews have also been dispatched to the flood-threatened north while others are in place at Dubbo.
Still more Fire and Rescue teams are operational at Moama, Barham, Warren and Moree, while pilotless aircraft and drones are being used to deliver situation reports on the Murray River and in the New England region.
Levee spills water in the Victorian town of Echuca
Water is spilling over a levee near the centre of Echuca, with authorities warning anyone left in the area to leave while they can.
The Murray River is forecast to reach levels just below the 1993 flood record overnight on Sunday and into Monday.
"We don't want to be rescuing people. Our strongest message is evacuate now," SES Victoria's Tim Wiebusch told reporters.
Gannawarra Shire Mayor Charlie Gillingham said water near Kerang and smaller surrounding towns was already high as of Saturday morning with the peak expected in hours.
"We've got water coming in from everywhere," Mr Gillingham told AAP.
Residents in Echuca are bracing for flood damage as the Murray River peaks. Source: Facebook / Ann-Marie Middleton
He said waters might not recede for a month or more.
Mr Gillingham said locals were sandbagging up until Saturday morning and there was concern nearby farmland would flood in the next 24 hours.
Rain and thunderstorms returned across the state overnight while western Victoria experienced the brunt of wild weather.
The SES received about 140 requests for help across the southwest from Geelong to Hamilton.
Three people were rescued after driving through floodwaters near Geelong and more than 85 millimetres of rain was recorded in nearby She Oaks.
"We know the single largest killer of flooding in Australia is as a result of people attempting to drive through flash floodwaters," Mr Wiebusch said.
"Please do not attempt that in the coming days."
The SES has received more than 8300 calls for help since the weather emergency began and more than 750 flood-related rescue requests.
Flood warnings remain for towns along the Loddon, Goulburn, Campaspe and Avoca rivers, with more rain and isolated thunderstorms forecast for the weekend.
