Nearly 70 flood warnings are in place across NSW as the focus turns to the far south Riverina region, with more rain expected to lash large areas of the state this week.
A low pressure system bringing heavy rain and thunderstorms is forecast to hit NSW from Wednesday to Friday, before weakening and being followed by more drenching rain on the weekend.
The downpours could cause renewed flooding along rivers in parts of the north west, central west and southwest inland catchments, which are already flooding from months of persistent rain.
"There's a danger of flash-flooding from intense bursts from severe thunderstorms ... as well bringing with them the potential for some destructive wind gusts," Bureau of Meteorology meteorologist Jane Golding said on Tuesday.
Some 300 people have already been evacuated from Moama, near the Victorian border, where residents are staring down the possibility by Friday of a flood higher than the 1993 event, the area's second worst on record.
Another evacuation was ordered north east of Moama near the Murray Valley Regional Park, with people told to leave by Tuesday evening before evacuation routes are cut off.
East Moama residents have been told to evacuate by 1pm Wednesday.
The State Emergency Service has dispatched more than 125,000 sandbags and set up two evacuation centres to accommodate up to 550 people in the region.
Nine aircraft are on standby throughout the state, along with five high-clearance vehicles, while up to 180 Defence personnel are available to assist in western NSW.
SES Assistant Commissioner Sean Kearns says the next 48 hours are crucial, with up to 3000 people on flood watch in communities near Moama.
Six flood rescues have taken place in the last 24 hours along with 50 requests for help, he said.
"The situation is not over and it's ... going to continue for several weeks to come," Mr Kearns told reporters.
"It might be blue sky but it doesn't mean it's not flooding and the rivers won't rise."
Premier Dominic Perrottet again warned many communities are in for a tough week.
"Our dams are full. Our rivers are full," he told reporters in Sydney on Tuesday.
"It's going to be a difficult time but we've got through difficult times in the past."
Emergency Services Minister Steph Cooke says the wet conditions are testing the resolve of flood-weary communities.
"This is what living through a third consecutive La Nina event looks like," she said.
"Our grounds are saturated and we are continuing to see rain and more rain".
Major flooding continues on the Macquarie River at Warren in the central west, with river heights slowly falling.
The Murrumbidgee River could reach major flooding at Narrandera on Tuesday night, where residents were told to evacuate over the weekend.
The water will then flow downstream to Hay, which could experience major flooding by the end of the week.
People in Forbes who were forced to evacuate after the Lachlan River burst its banks last week have been told they can return with caution but have been advised to stay out of floodwaters.
Prime Minister Anthony Albanese and Mr Perrottet visited the region on Monday.
Mr Albanese warned flood threats were likely to continue for some time.
"We are living in very dangerous times in the days and weeks ahead," he said.
Mr Perrottet called for vigilance in flood-threatened communities through summer and urged people to follow the advice of emergency services.
