The New South Wales Emergency Minister is warning Saturday will be "danger day" for Sydney and surrounding areas, with two more significant rain events set to sweep the state.
Most of the state's river catchments are under a flood warning or a flood watch, particularly inland, after several months of significant rain.
Emergency Minister Steph Cooke said it would not take much rainfall to exacerbate the flood situation in the west, with flash flooding a major concern.
"Our catchments are saturated, our dams are full, and our rivers are already swollen," she said.
"Some of those western communities, in particular, have been in flood for 12 months now."
Rain has eased in inland parts of the state today but the weather bureau is forecasting a "significant and elevated flood risk" over the coming days with two systems set to develop.
Senior forecaster Gabrielle Woodhouse said the first was predicted to worsen from Thursday afternoon, with thunderstorms developing in the far west, including supercells in the south west.
Ms Woodhouse said a second system was expected to move across parts of the Hunter, Sydney, and Illawarra on Saturday and Sunday.
"This is quite a significant and serious system, as we are looking at widespread rain and thunderstorms in that system," she said.
"We are looking at renewed and prolonged flooding across parts of inland NSW, but we are expecting that flood risk to move further east on the weekend."
Major flooding is possible on the western slopes this weekend, including in the towns of Bathurst, Gunnedah, Wee Waa, Warren, and Forbes and is expected to be worse than what has already occurred over the past 12 months.
The State Emergency Service said those towns were the focus of its preparation efforts, given the high risk of flash flooding.
SES Commissioner Carlene York said, further east, the most recent warnings for the Hunter put that region at risk of major flooding.
"That flood risk may go from the Hunter across to the Central Coast, so there are large areas of the state that are being impacted by these weather events," she said.
Motorists are being urged to take care and be prepared for extra travel time, particularly as families return from school holidays over the weekend.
There is also concern for the Bathurst 1000 supercar race where 200,000 people are expected to attend, with some of those camping in sodden campgrounds.
Number of isolated properties grows
More rural areas are also being isolated in western New South Wales as flooding worsens, with farmers resorting to moving livestock on boats as their properties sit completely under water.
People are getting cut off as roads with water over them are shut, making moving around the region a difficult task.
SES Southern Zone spokesperson Scott McLennan warned the situation would only get more dangerous.
"It's just going to get wetter and wetter over the next couple of months and weeks, it's just a reality that we are facing," he said.
"Are we at the worst? We don't know but we do know that there is more water coming."
Mr McLennan said people could be cut off for quite some time, as the SES prepared for a prolonged maintenance period of food, fodder, and medicine drops.
Backup crews have been brought in to assist, as some have already been cut off for several months.
Aircraft, high clearance vehicles, and 500 SES volunteers are out in the field.
Race against time
Mixed farmer Richard Bootle said he had purpose-built levees around his property at Nyngan, north-west of Dubbo, to withstand previous flood heights of 2016 and 1990.
"I think the Lismore floods earlier this year taught us that the fact you're above a previous flood record, in the time of climate change, just doesn't make any difference," he said.
Mr Bootle said he was "scared" the levees would likely fail if 150mm, which was predicted across the Bogan River catchment, eventuated.
His stock and equipment have been moved to higher ground and he is worried he will not be able to harvest the winter barley crop.
Removalists have arrived to begin taking away furniture and valuables from his home.
