About 6,000 people have been forced to evacuate their homes in the NSW Hunter Valley amid fears that flood waters could swamp the town of Maitland.

Police were on Sunday night warning local residents to get out as the Hunter River began to reach its peak, although some locals were resisting efforts to have them leave.

While the torrential downpours and gale-force winds of Friday had eased by Sunday, the focus turned to the dangers posed by flood waters, with the Hunter Valley centres of Maitland and Singleton preparing for the worst.

Main roads into Maitland were cut by the rising flood waters, and the New England Highway was closed to all traffic but emergency service vehicles.

Emergency services personnel and volunteers were conducting a desperate sandbagging operation to fortify the levee, with 100 Australian Defence Force personnel deployed to assist with the efforts.

Police were using loud hailers in the suburb of Lorn warning residents to get out.

The SES and police said rising flood waters on the outskirts of Maitland had breached the levee, reaching the flood peak of 11.4 metres at about 10.30pm (AEST).

SES spokesman Philip Campbell said a complex series of spillways and control banks were holding for now.

"They're doing as they are supposed to and some of those are in fact spilling over," Mr Campbell said.

He said the flood waters had not yet peaked at the main levee.

But NSW police were warning residents in Central Maitland, South Maitland and Lorn to get out of the area, saying flooding of low-lying areas was imminent.

They said residents should not rely on levee bank readings in Lorn and the Maitland CBD, but should instead adhere to advice from the emergency services.

"Levee banks in that area are becoming increasingly soggy and likely to give way at any time tonight," a police spokesman said of low-lying parts of Maitland.

Several residents were refusing to leave their homes, he said.

Mr Campbell said he understood why those behind the levee might be doubtful about the danger, but he urged them to take the warnings seriously.

Resident "John" said the city of Maitland resembled a ghost town.

"It's eerie actually, the lights are on, the street lights are on, the traffic lights are blinking away for no one," he told ABC radio.

Emergency Services Minister Nathan Rees said about 2,000 SES volunteers were in the field, with the SES responding to more than 11,400 calls for help in the Hunter, Central Coast and Sydney Metropolitan areas since the storm situation began.

He said about 6,000 people were being evacuated from the town and district of Maitland.

The death toll from the three days of wild storms reached nine on Sunday as police found the body of 45-year-old Adamstown man, Wayne Bull, who was swept into a stormwater drain in the Newcastle suburb of Lambton after getting out of his car on Griffith Road on Friday night.

At the peak of Friday's wild weather, five members of the same family were swept to their deaths when a section of the Old Pacific Highway collapsed under their vehicle and it was hit by a "wall of water" at Somersby, near Gosford.

The bodies of 30-year-old Adam Holt and his long-term partner Roslyn Bragg, 29, were recovered from Piles Creek on Sunday, while the bodies of their two daughters, Madison and Jasmine, aged two and three, and their nephew Travis Bragg, nine, were recovered on Sunday night.

"It's a massive loss for all of us ... it's not fair, not fair on anybody," Andrew Holt's sister Fiona Holt told TV crews.

Further north, Robert and Linda Jones were killed when their vehicle was washed off a flooded bridge at Clarence Town, while a 29-year-old Heddon Greta man died when a tree fell on his ute at Brunkerville, Lake Macquarie, about 6pm (AEST) on Sunday.

NSW Premier Morris Iemma, who has already been in the area and will again visit flood-afflicted areas in the Hunter on Monday, described the damage in Newcastle as worse than that caused by the city's 1989 earthquake.

"Construction sites and scaffolding, debris on roads, abandoned cars, homes that were damaged, trees having fallen on homes, extensive damage. It was quite disbelieving," he told the Seven Network.

Prime Minister John Howard on Sunday offered additional financial support, and his condolences, to people affected by the storms.

"I know I speak for every Australian in saying that the country is thinking of you and we're heart broken by the loss of lives and the tragic circumstances in which a number of people have lost their lives ... (it's) the, tragically, human side of something such as this," he said.

"It is an immense disaster."

Governor General Major General Michael Jeffery will also visit Maitland on Monday.

"On behalf of all Australians I extend my deepest sympathy to the families of those who died and wish to acknowledge the work of the various emergency service personnel and others involved in rescuing and supporting those in need," he said.

Power was restored to 30,000 homes and businesses on Sunday but more than 75,000 throughout NSW remain in the dark after the storms.

A spokesman for Mr Iemma said a specially-convened "recovery team" will meet with local mayors in the Hunter and Central Coast regions to establish where the worst of the problems are and how best to get financial assistance to those who need it.