Rain has eased over much of NSW but dozens of rivers are flooding and evacuation orders are in place as authorities forecast another rain system to arrive midweek.
People across the state were forced to flee their homes on the weekend amid rising floodwaters and thousands of others are poised to leave if ordered as dams spill and river peaks move downstream.
Seven rivers are experiencing or may experience major flooding in the coming days, the Bureau of Meteorology's Dean Narramore says.
Major flooding is occurring along the Murrumbidgee River with people in Gundagai, Gunnedah, Wee Waa, Warren and Forbes on high alert.
"Events can quickly change. In some areas we're anticipating anywhere between 30 to 75 millimetres of rain," Fire and Rescue NSW senior official Ken Murphy told ABC on Monday, referring to the Forbes area.
He also warned dams throughout the state could overflow throughout the week.
There are more than 100 flood warnings in place and 16 emergency warnings across NSW.
NSW State Emergency Service received more than 1000 calls for help on the weekend and responded to 44 flood rescues including 12 vehicles stuck in flood waters.
Premier Dominic Perrottet says the areas of most concern are in the state's west and the Hawkesbury-Nepean area and has urged everyone to heed warnings.
"The dams are full. The rivers are full. There is water right across the state," he told reporters.
The BOM says no heavy falls are expected in the next couple of days but areas east of the Great Dividing Range will receive patches of rain.
The reprieve will be short-lived, with another system expected to bring rain from Wednesday to Friday.
SES Commissioner Carlene York warned people not to become complacent because the rain had stopped.
"We're seeing flash flooding and serious riverine flooding rising," she told Sydney radio 2GB on Monday.
"Just because it's not raining, it doesn't mean those rivers aren't rising - water is still flowing into our catchment areas."
The SES issued new evacuation orders overnight for low-lying areas along the Hawkesbury River and an evacuation centre has been established at North Richmond while flooding continues further west and south.
Moderate to heavy rainfall since Saturday caused significant river level rises across the Hawkesbury-Nepean Valley, triggering moderate flooding at North Richmond and Windsor and minor flooding at Penrith and Sackville.
Along the Macquarie River, moderate flooding is occurring at Dubbo and Narromine, with major flooding at Warren.
The Macquarie River at Warren Town could reach around 9.60 metres late on Monday and into Tuesday, bringing major flooding.
Agriculture Minister and Dubbo MP Dugald Saunders says there are many road closures in the district as vast swathes of water envelope the landscape.
"The deluge of rain that happened turned what are normally just little creeks of less than a metre into rampaging rivers of 30 and 40m wide through paddocks," he told 2GB.
"There's a lot of crops that will be lost.
"We're just bracing for another weather event ... from Wednesday to Friday."
Mr Saunders urged landholders to report any flood damage to their properties, including land, infrastructure and animals.
"Since the heavy rain began last week, we have already assisted three farmers in western NSW with emergency fodder drops because their livestock was stranded," he said in a statement.
"We expect this number to increase in the coming days."
© AAP 2022