New South Wales is facing a "dangerous" 48-hour period as a severe weather front brings rainfall in excess of 150mm to flooded communities.
Lismore residents are facing a third major flood in eight months, with prepare-to-evacuate warnings in place for south, north, and lower north Lismore.
These communities are being asked to evacuate by 9am on Monday morning.
Evacuation orders for Moree have been issued and 150 Australian Defence Force personnel have begun setting up a 'base camp' to assist local authorities.
The flood level along the Gwydir River was expected to peak at 10.7m on Sunday afternoon, exceeding the flood event Moree experienced in March 2021.
A major flood warning has been issued for Lismore, with the Wilsons River expected to reach 9.7 metres on Monday afternoon.
There are 130 flood warnings across New South Wales, with 22 at emergency level.
In the 24 hours to Sunday afternoon, the NSW SES had 395 requests for assistance and 31 flood rescues.
The Bureau of Meteorology's Jane Golding said a low-pressure system off the coast of southern Queensland was bringing heavy rainfall.
"That system has produced pretty widespread totals of 100mm from the New South Wales border up to Bundaberg," she said.
"That is the system we are concerned about for the Northern Rivers for the next 24 hours."
Christie Johnson from the Bureau said that system was predicted to cause significant flooding in the north of the state.
"If it stays offshore it will be closer to 50mm, but if it comes inland it could be in excess of 100mm," Ms Johnson said.
Gunnedah in the state's north-east is experiencing major flooding, with a peak of 8.5m on Sunday evening.
Ms Golding said another weather front moving through South Australia would bring heavy falls to inland New South Wales.
Condobolin and Hay are expected to reach major flood levels on Monday as a result.
NSW Emergency Services Minister Steph Cooke said the state was facing unprecedented flooding.
"What we are currently experiencing is more flood threats, in more communities, in more locations than at any other time this year," Ms Cooke said.
"We are facing a very dangerous 48 hours right across New South Wales."
Evacuation centres have been set up in Moama, Deniliquin, Moree, Tamworth, and Gunnedah.
More flooding is possible on Sydney's Hawkesbury-Nepean River, while river rises are continuing to impact Moama and Narrandera in the south.
The New South Wales Central West was hit by heavy falls, with Mudgee recording 77mm in the past 24 hours while Cowra received 37mm.
'We just get up and keep on going'
An initial major flooding warning has been released for Lismore, with flood levels expected to reach 9.7m along the Wilsons river on Monday afternoon.
Rainfall is expected to intensify over the Wilsons River catchment throughout Sunday.
The forecasted heavy rainfall is expected to cause further river level rises into Monday with moderate flooding expected on Monday morning.
Lismore mayor Steve Krieg said further flooding would be devastating for the community, especially for recently opened businesses in the CBD.
"There are people who have moved back to their homes, spent thousands of dollars trying to rebuild their lives and here we are," he said.
"What do you do? How do you tell people it's going to be okay when you don't know yourself that it's going to be okay?"
SES and police are door-knocking lower-lying areas.
Lismore's Heidi Green runs the Furniture Wiz store and says her team has been busy getting machinery upstairs and getting supplies and gas bottles.
"We've just brought UHF radios so we can be on the bandwagon if we need to be able to talk with other people," she said.
The owner of the Northern Rivers Collectables antique shop, Adam Bailey, says the floods have taken a toll on him and his business.
"We haven't stopped. We haven't stopped cleaning, we haven't stopped moving stuff around," he said.
"And I now live in the shop here so now this is my whole home.
"It's a bit of a drama and we just hope it doesn't come up anywhere near the last big one we had."
Mr Bailey said he loved Lismore and would never leave, but he wouldn't mind a break from the downpour and flooding.
"I'd just like to have a day off," he said.
"I'd like to be able to go somewhere and not have to think about it but unfortunately, you know Lismore, that's what we're all about.
"And we just get up and keep on going."
In February, the Wilsons River reached 14.4m resulting in multiple deaths, widespread destruction, and billions of dollars worth of damage.
Watch and wait for Moama
Residents in Moama near the Victorian border are waiting to see if the flood level exceeds the 1993 levee.
Overnight, the SES carried out two flood rescues in the town with one property requiring assistance with evacuation at 2am.
Linda Perrett lives 50m from the levee and believed it would hold the floodwater back.
"I'm confident in the levee, I've been watching it most mornings and I think there is a lot of positivity in how this will eventuate," she said.
Michael Falzon owns a caravan park on the edge of town and has lived in the area for 45 years.
He built a kilometre-long sandbag levee to help protect his property but he was still worried about the situation.
"You get up in the middle of the night and wonder if it has come up a metre or if it is going to seep through the sandbags and break the bank," he said.
