Sailor missing, campers stranded in storms

The search for a sailor thrown from a yacht in rough seas off the NSW mid-north coast has been suspended amid wild weather.

Unrelenting rain has also forced a large group of campers to spend at least one more night stranded on the NSW south coast, surrounded by rising floodwaters.

The yachtsman was tossed into the sea on Wednesday afternoon when a huge wave struck his vessel near Broughton Island.

Rescue helicopters dispatched to help find the man in his 60s were forced to turn around on Wednesday night due to poor weather and heavy seas.

Police boats were also required to help two more yachts in strife amid woeful conditions off Broughton Island.

Rescue crews are expected to decide on resuming the search for the missing yachtsman on Thursday morning.

Unrelenting rain has made it difficult for helicopter crews to reach a group of 16 adults and two children who've been isolated at the Bendethera Valley campground west of Moruya since Sunday.

National Parks rangers are with the group who have adequate food and water for at least two days, SES spokesman Dave Webber told AAP on Wednesday night.

"We're looking to send a helicopter there on a reconnaissance mission tomorrow to make sure they're OK and assess access to the site," he said.

Further north, at least 70 residents in Raymond Terrace are also spending the night away from home after they were ordered to evacuate with nearby Hunter River expected to peak.

The small town of Torryburn remains isolated by floodwaters which inundated a bridge, while 300 people have been isolated by minor flooding near Colo, northwest of Sydney.

Residents meanwhile returned to homes in Dungog after evacuation notices were issued on Tuesday night to about 10 streets in the Hunter region town.

Local woman Jodie Francey said people in the town were on tenterhooks because of the devastating floods which hit the town in April, but conditions didn't seem as bad.

"I think the amount of rain gave people a case of deja vu ... there are still people that aren't in their homes," Ms Francey told AAP.

Emergency Services Minister David Elliot echoed the sentiment, saying the heavy rain was only "10 per cent" of what was seen in the April storms.

Mr Elliot said he was delighted to learn that a person was issued with an infringement notice for negligent driving after driving through floodwaters.

"It was only nine months ago that we saw a tragic loss of life ... in the April storms. I would've thought that the community concern and anxiety caused by those deaths would've meant that we shouldn't have this problem," he said on Wednesday.

He's joined NSW police and the SES in their calls for people to avoid driving through floodwaters and only to travel if necessary.

Across the state, rescue crews carried out 28 rescues from floodwaters while there have been nearly 2000 calls for help since Tuesday.

Most of these related to leaking roofs and property damage, but volunteers responded to everything from cows blocking traffic to airlifting a 42-weeks pregnant woman to hospital, the SES said.

Several severe weather warnings remain in place for the Hunter region, including major flood warnings for the Williams and Paterson rivers, but the weather bureau predicts the heavy rain will subside on Thursday.

It's estimated a month's rain has fallen in the past two days, with more than 200mm falling in less than 24 hours along parts of the mid-north coast.

Weather conditions are expected to ease significantly on Thursday and floodwaters tipped to begin subsiding late in the afternoon.