A surfer has died after being slammed into a storm water drain at Collaroy on Sydney's northern beaches.
The 44-year-old man was swept up in a huge swell that pushed him under the drain.
He was pulled free by an off duty lifesaver who performed CPR.
He was taken to Royal North Shore Hospital but died this afternoon.
Meanwhile, torrential rain forced residents in low-lying NSW South Coast communities to evacuate their homes while hundreds of calls for help were made to State Emergency Services (SES) in Sydney.
Up to 300 millimetres of rain fell in some areas at the weekend and while it eased this morning, swollen rivers continue to pose significant risks.
The NSW SES said it had received 1,600 calls for help since Friday evening, with about 700 of those on the South Coast and 550 in Greater Sydney.
It yesterday issued urgent evacuation orders to Shoalhaven communities, including the Moruya CBD and Sussex Inlet.
"Fortunately only one family has had to be found emergency accommodation," said Premier Gladys Berejiklian.
"Everybody else who's asked to be evacuated has managed to find accommodation on their own."
The Moruya CBD evacuation order is expected to be lifted today.
Most of the 40 rescues since Friday night — six of which occurred overnight — were from cars driving into flood waters.
"We have done a number of animal rescues, livestock, sheep, horses and got them to higher ground so I'd remind those property owners to keep an eye on the weather," said SES Commissioner Carlene York.
Meanwhile, most of the calls the SES received last night in Sydney were for fallen trees and leaky roofs.
Commissioner York reminded residents not to park cars under heavy branches during wild weather conditions.
Cabramatta resident Alma Baltazar said strong winds overnight brought down a tree which damaged a brick wall outside her unit.
"Last night it was a really windy night. It was just horrible, everything was shaking. My unit was shaking," Ms Baltazar said.
"My window was shaking and I heard a big bang so I came out to look and I saw the tree just fell."
Ms Baltazar said she didn't expect the damage to be so extensive.
"I thought, oh no, because I saw someone's car — I'm hoping that they should come out soon and have a look."
Endeavour Energy said 3,500 customers were still without power, after a peak of 13,500 experienced power outages last night.
Janine Cullen said extensive flooding was hampering the ability of crews to respond to call outs, with the worst affected areas in the Shoalhaven.
"We've got about 1,200 out in the Shoalhaven and probably another 135 up the [Southern] Highlands at Sutton Forest and Robertson, but the worst hit area is Callala Bay [with] about 570 [calls]."
Snow also fell overnight in Blackheath in the Blue Mountains and in Barrington Tops, in the Hunter region, with locals describing it as a winter wonderland.
Kelly Davis from Aussie Ark, near Barrington, said snow was coating the ground this morning.
"Snow has fallen quite thick overnight … blanketed everywhere," she said.
"It looks to be around five or 10 centimetres or so."
The Bureau of Meteorology (BOM) said wind gusts of up to 87kph were recorded at Bellambi in the Illawarra, while 85kph gusts were recorded at Sydney's North Head and 82kph at Kiama on the state's South Coast.
Strong winds are expected to hit the Mid-North Coast later in the afternoon.
There are also warnings for significant beach erosion along parts of the the Illawarra, Sydney and Hunter coast, with waves expected to exceed 5 metres.
The wild weather also forced the closure of several schools in the state's south, including Windellama Public School, Tarago Public School and Captain's Public School.
The SES said there was still a moderate flooding risk on the Shoalhaven River with a major flooding forecast for the early afternoon.
It is expected to peak at Nowra and Terara at 1pm, with floodwaters also predicted to inundate low lying areas around Shoalhaven Heads.
Flood levels at Nowra, south of Sydney, reached a 30-year high after with the Shoalhaven River rose to 4 metres.
The river peaked at 9:00am and is expected to remain high for most of the afternoon.
Hydrologist Alex Clifton from the Bureau of Meteorology said floodwater at the top of the valley had travelled downstream to Nowra and Terara.
"The Shoalhaven river is fairly resilient to flooding in terms of the impacts on population, so as a result, we haven't seen anything of this magnitude since 1991," Mr Clifton said.
"A major flood in general means major road arteries are cut off and there's generally inundation to floor level of a significant amount of properties — That's what's occurring at Nowra at the moment."
Nowra is expected to be flooded until at least Tuesday.ABC