Schools are closed, roads are cut off and communities already affected by floods are on alert in New South Wales northern, Central West and southern border areas as more rain has been forecast over the weekend.
The State Emergency Service issued two emergency warnings urging residents in north-east Narrabri and Terry Hie Hie, near Moree, to move to higher ground.
Residents in low-lying areas of Moree and North Gunnedah were also told to prepare to evacuate.
In the 24 hours to 9am on Friday, Terry Hie Hie received 123mm of rain, Moree received 108mm and Upper Horton 120mm.
Meanwhile, in the state's Central West, Forbes recorded 39mm.
Minister for Emergency Services Steph Cooke said more widespread rain forecast over the weekend had authorities on alert.
"Our rivers are full, our dams are full," Ms Cooke said.
"There are many dams which are currently or will spill over the weekend and any additional rainfall onto already saturated landscapes increases the risk of both riverine and flash flooding."
Since 6pm Thursday, the NSW SES received 384 requests for assistance and 12 flood rescues were carried out.
"We have ADF, Surf Life Saving, RFS and Fire and Rescue that are all in the area helping out with those operations," SES's Cindy Hewson said.
A NSW RFS helicopter rescued two people after their car became bogged and trapped in floodwaters near Moree.
The state's north west and southern border areas remained the worst-affected areas.
Ms Hewson asked these communities "to have their emergency plans ready and start preparing their homes".
Moree Business Chamber president Dibs Cush received up to 250mm of rain overnight at her property, 25 kilometres south-west of Moree.
"That was a wild and woolly night — we haven't slept much at all," she said.
"We've had between 160mm here at the house and 250 at the furthest point, sort of west, on the farm.
"It could've been more than that because that's as much as the rain gauge holds.
"Pretty much every single field is full of water and we finished planting cotton on Wednesday."
"The boys are trying as hard as they can to pump the water off the fields but the dams are all full because they've already had several storm and rain events this year, so there's really nowhere for it to go."
'Life-threatening' flash floods
Morgan Pumpa from the Bureau of Meteorology said more thunderstorms and possibly heavy falls were forecast over the next few days.
"The areas with the chance of the intense rainfall – which may lead to dangerous and life-threatening flash flooding – over the next several hours [include] the North West Slopes and Plains [and] areas such as Moree, Warialda and Bingara," she said.
"This system can be quite unpredictable, so we have seen some significant rainfall already overnight."
Ms Pumpa urged people to "keep an eye on the radar and the warnings".
Residents in Gunnedah, Narrabri, Mullaley and Boggabri are being warned flash flooding is a possibility, while a major flooding event is now being considered likely at Gravesend.
There are 84 flood warnings, including 10 emergency warnings, in place across the state.
Levee will hold, mayor says
The Murray River at Moama in southern New South Wales has swollen to 94.62 metres (above sea level) and the BOM said it could peak around 95 metres overnight Sunday into Monday.
At Echuca the Murray could reach 94.80 metres on Sunday and trigger the highest flood since 1993.
A 2.5-kilometre levee has been built to protect the town, but rain that has fallen inside the protected zone will need to be pumped out.
Murray River Mayor Chris Bilkey said he was confident the town's levee, which was built after the 1993 floods and has not been tested since, would hold ahead of the expected peak.
"There are outlying areas to the east of Moama that are already inundated – and they always would be in a flood of this sort – but the expectation is that it will hold for a majority of the town," Cr Bilkey said.
