The NSW State Emergency Service is warning of flash flooding, riverine flooding and coastal erosion with torrential rain forecast across the Illawarra, South Coast and Southern Highlands until Tuesday.
Moderate and minor flood warnings have been issued for swollen catchments as an east coast low weather system dumps heavy rain on the region.
In the past 24 hours, at least 366 millimetres of rain has fallen at Brogers Creek, 298 millimetres at Darkes Forest and 262 millimetres at Fitzroy Falls.
The Shoalhaven River at Nowra and Terara peaked at near moderate flooding on Sunday, but fell throughout the afternoon taking it to minor flood levels.
The Bureau of Meteorology warned renewed rises were possible.
A minor flood warning was also issued for the St Georges Basin at Sussex Inlet.
While levels were steady and below minor flooding, authorities said it could reach 0.9 metres at high tides on Sunday and Monday evenings.
A severe weather warning for heavy rainfall and damaging winds is also in place across the region.
"The forecast is for the east coast low to continue to develop and track southwards towards the Hunter coast and the Sydney coast over the next 24 hours," Bureau of Meteorology senior forecaster, Jane Golding said.
"It will remain until Tuesday before shifting offshore and what that means is widespread rainfall continuing.
Youths isolated at Bargo
The SES has carried out 29 flood rescues across the state since Saturday and is working to evacuate several youths from a recreation camp in the Southern Highlands.
"A number of youths are isolated at a recreation camp in the Bargo area and we’re putting in plans to evacuate them today," SES Commissioner Carlene York said.
"They are safe but it is a reminder of how quickly these weather events can affect your community.
She said dozens of homes were also damaged in the Illawarra on Saturday night by strong winds.
"Last night we had around 40 houses affected in the Bellambi-Corrimal areas where roofs were affected, and we had to go and assist residents. Ms York said.
Delay travel plans
Emergency Services Minister Steph Cooke has urged residents to reconsider school holiday travel plans until the weather abates.
"I’d just ask people to stop and have a bit of think about where they’re going and how much they’re moving over the next few days because we don’t want any lives lost through this event."
