Sydney and southern NSW are set for another soaking and authorities are keeping a close eye on the almost-full Warragamba Dam as damaging winds and rain build off the state's coast.
Parts of the state have copped heavy falls during the weekend, with 61mm of rain recorded at Lightning Ridge on Sunday morning while at Frenchs Forest, in Sydney's north, 31mm had come down with more expected into Sunday night.
Dangerous, strong winds gusting up to 90km/h are also forecast for coastal areas as a low-pressure system builds over the ocean near the Illawarra region, but one of the biggest concerns for forecasters and hydrologists is the Warragamba Dam, which is at about 98 per cent capacity.
"It's possible that the dam may spill, but it depends on how much more rain it gets and how widespread across the catchment that rainfall is," a Bureau of Meteorology forecaster told AAP.
Flood watches have also been issued for several river catchment areas from the Tweed to the Illawarra but the BoM is waiting for further rainfall data before issuing warnings, the forecaster added.
Unlike the devastating storms earlier this month, which left two men dead and a multi-million dollar clean-up bill, surging king tides are not forecast.
During that weekend of wild weather waves ripped parts of the coast into the sea and left a dozen beachfront Collaroy homes teetering precariously on eroded coastline but this time they are not predicted to be anywhere near as high or strong.
"Any sort of erosion is much less of a problem," the forecaster said.
The foul weather is expected to hang around the state's south early in the week before heading towards Bass Strait.
A severe weather warning has been issued for the Illawarra and south coast on Sunday, with it expected to remain in place for part of the region on Monday.
"Heavy rain which may lead to flash flooding is possible," the BoM has warned.
During the last deluge, more than 300 flood rescues were carried out - and more than 30,000 insurance claims worth a combined $235 million across east coast states and Tasmania were lodged in the aftermath.
