A swollen Shoalhaven River has prompted the worse flooding the area has seen in almost 30 years.
Torrential rain and strong winds have battered the New South Wales south coast, prompting evacuations, as the Shoalhaven River reached its peak on Monday.
At least 1,600 people called emergency services for help across the state over the weekend, including 963 calls by 8:30am on Monday morning.
About 400 of those were in Sydney and the Blue Mountains overnight as strong winds and heavy rain toppled trees, damaged roofs and flooded roads.
But the south of the state is bearing the brunt of the weather, with flood evacuation orders in place for Moruya CBD, Sussex Inlet, and parts of the Shoalhaven, including Terara, East Nowra, North Nowra, and Worrigee.
Residents of these areas were advised to leave the area late on Sunday after heavy rain led to flooding along the Deua River.
Up to 200 millimetres of rain hit a number of towns including Moruya, Nowra and inland at Captains Flat over the 24 hours to Sunday evening, with up to 300 millimetres in isolated areas.
By Monday morning, flooding at the Moruya River was minor, with SES Commissioner Carlene York saying the Moruya CBD evacuation order would lift later on Monday.
According to a Bureau of Meteorology flood warning issued just before midday on Monday, the Shoalhaven River peaked at 4.13 metres at Nowra about 9am and was at 4.08 metres mid-afternoon and falling with moderate flooding.
It peaked at 3.89 metres at Terara and is was at 3.83 metres mid-afternoon.
The BOM said the area is experiencing the worst flooding it has seen since June 1991.
Some 40 flood rescues have been required across the state, AAP reports.
An SES spokesperson said most calls came from Berry, Nowra, Broughton Vale and Gerringong, with more than 20 homes at Broughton Vale near Berry cut off by floodwater.
The spokesperson said the focus on Monday will be the Shoalhaven.
“We will issue an all-clear when it is safe for people to return home," they said.
Ms York warned people on Monday not to walk, drive or swim through floodwaters, which were often fast moving and polluted with debris.
"It's fast-flowing, so there's lots of refuse and tree material coming down in that (Shoalhaven) river so it's quite dangerous," she told reporters.
A severe weather warning for damaging winds and surf also remains in place across Sydney, the Central Coast, Newcastle and the mid-north coast region up to Kempsey, with gusts of up to 90 km/h moving up the coast.
People in these regions are also being advised to stay out of the water, with a hazardous surf expected along the coastline.
About 2,000 Endeavour Energy customers in NSW remained without power on Monday afternoon, as storms created 270 electrical hazards from fallen trees and branches.
"Localised flooding on parts of the south coast are hampering crews from accessing damaged parts of the network in some areas," the company said in a statement.