Four people were rescued from floodwaters in Newcastle on Sunday afternoon as heavy rain swept across the city.
The State Emergency Service was called to rescue people from cars at Maude St, Mayfield West, Tourle St, Mayfield West, University Drive Callaghan and Turton Road, New Lambton.
All of the persons were rescued without injury.
Newcastle State Emergency Service had received 50 calls for assistance by 5.30pm, Maitland and Port Stephens units 15 each and Lake Macquarie 11.
Motorists are advised to be on the lookout for flash flooding at Sandgate, Mayfield, Wallsend, Agenton and Callaghan.
Williamtown weather station recorded 104 millimetres of rain between 9am and 5pm while Tighes Hill recorded 110. Most other areas recorded about 60 millimetres.
The Bureau of Meteorology predicts a low-pressure system will stay close to the NSW coastline throughout Sunday and Monday resulting in a fresh erosion threat to the region's beaches.
"The rainfall is likely to extend into central and southern NSW for Sunday, with today likely to be the wettest day for northern and central coastal areas NSW, including Sydney, bureau forecaster Grace Legge said.
"Hazardous surf conditions are likely to ease later Wednesday as the system pulls away from the coast."
The City of Newcastle spent the weekend reinforcing parts of Stockton foreshore for the predicted large swell.
Homes will also come under renewed threat at Wamberal.