Australia Weather News

There was a downpour of 204 millimetres at Nowra. - ABC

Residents on the New South Wales South Coast hit by flash flooding have been warned conditions will get worse today.

A complex coastal trough is causing strong winds and a continuing onslaught of rain, and the Bureau of Meteorology (BOM) said the deluge will continue.

The State Emergency Service (SES) has already received at least 441 calls for help over the past 24 hours, mostly in the Illawarra and Southern Highlands region.

BOM warnings for damaging surf, wind and heavy rainfall are in place for the Illawarra, Mid North Coast, Hunter, Sydney metropolitan, South Coast and Southern Tablelands.

Flood warnings have been issued for several towns on the South Coast.

The BOM said the communities most at risk were Moruya and Shoalhaven.

"We've had a lot of rainfall over the Shoalhaven River and we're very concerned about the community of Nowra who are still having rapid river level rises upstream," BOM senior flood hydrologist Justin Robinson said.

The water level at Moruya is expected to peak at 2.7 metres — a moderate flood level — at about 5:00pm today.

The Moruya CBD is most at risk, with emergency services flagging evacuation centres may be opened.

"Once we get to [a] moderate to major forecast we try and give as much warning as possible for evacuations," SES Commissioner Carlene York said.

"It does depend and it does come up quite quickly on how heavy that rainfall is.

"We are there on the ground watching the rivers, watching any rises."

Sussex Inlet's flood level is expected to peak at 1.5m at about 10:00pm today.

The community of Shoalhaven will be impacted by moderate flooding which will peak at about 4:30pm.

The town of Broughton Vale in Shoalhaven has been isolated by flooding, with 23 homes impacted. However, the community will not evacuate at this point.

The SES said it had received more than 770 calls for assistance since 7:00pm on Friday and done 18 flood rescues.

Large parts of the NSW South Coast have received between 100mm and 200 mm of rain, with some locations receiving up to 300mm.

Mr Robinson said the BOM was concerned about the situation.

"We really feel for those residents of the South Coast who have gone through so much in the past year," he said.

"But we're hopeful that the worst of the flood producing rainfall has fallen and now we're just keeping a very close eye on those river levels."

Surf conditions remain dangerous and wind speeds will also pick up, with gusts of up to 90 kilometres per hour possible in some areas.

The winds will move up towards the Sydney metropolitan area and parts of the Central Coast late this afternoon.

There is a warning about coastal erosion for parts of the Illawarra and the South Coast from late today.

People are being advised about potential dangerous beach conditions and also being told to avoid floodwaters and fast-flowing creeks and rivers.