Clean-up starts after storms batter NSW

A big clean-up is under way after gale force winds wrecked houses, cut power and felled trees across parts of Sydney and the NSW south coast.

In the state's north around 20,000 people remain isolated by floodwaters but conditions are easing as swollen rivers disgorge their extra loads into the sea.

The State Emergency Service had received nearly 5000 calls for help from across the state by late Sunday evening.

More than 2000 were in the Sydney area where 100kmh winds resulted in an asbestos scare.

In the city's southeast, savage gusts extensively damaged the roof of the RSL club in Malabar, causing sheets of asbestos to fly onto nearby homes and roads.

A number of streets were blocked off by Fire and Rescue NSW crews on Sunday, as private contractors were tasked with cleaning up the area.

Residents were told not to panic about air contamination but to contact the NSW Environment Protection Authority if they noticed asbestos near their homes or backyards.

"There is no need for residents to be concerned that the air they breathe is contaminated," Superintendent Paul Bailey told Fairfax Media.

Elsewhere in Sydney's east, locals described wind gusts that felt like "mini tornadoes", which damaged a primary school and tore part of the roof off Fox Studios.

The SES also responded to around 400 calls on the south coast, where Kiama was the hardest hit, SES spokeswoman Becky Collings said.

"We had three homes that were completely written off, and seven others that suffered significant damage," she told AAP.

"We had a lot of trees down and roof damage."

SES spokesman Phil Campbell said severe storms in parts of western Sydney and the Illawarra on Sunday night had not resulted in too many calls for help.

He said SES crews and firefighters had been busy making temporary repairs to wind-damaged houses at Malabar, Kiama and Narellan.

Mr Campbell said the SES had performed 75 flood rescues since the low pressure system hit the state on Friday.

One of those was of seven campers rescued by helicopter on Sunday morning from their camping site beside the Clyde River near Ulladulla on the south coast after they were stranded by rising waters.

Around 20,600 people in 39 separate communities remained isolated by floodwaters on the NSW mid-north coast on Sunday night while about 4150 people were still affected by evacuation orders or warnings.

Some properties at Port Macquarie flooded on Sunday morning as the Hastings River swelled to its expected peak of 1.8 metres.

The Macleay River at Kempsey peaked at 7m on Sunday near the town's CBD, about 30 centimetres below expectations, causing some inundation but not the feared flooding of many shops and homes.

On Sunday night the main affected flood areas were downstream of Kempsey and downstream of Grafton on the Clarence.

"The flooding is easing, all the rivers have peaked past the major towns and are now moving down towards the mouths of the various rivers," Mr Campbell said.

A few people with medical issues had been moved from isolated communities which would be resupplied with essential items if required by flood boats or helicopters, he said.

Ausgrid said around 1000 homes were expected to be without power on Sunday night across Sydney's north and the Central Coast after the storms cut power to more than 20,000 homes.

Two people died in the floods including a man found in his submerged car at Mylneford, northwest of Grafton, and a 17-year-old boy swept into a drainpipe while collecting golf balls in the town of Kew, near Port Macquarie.