Singleton CBD is under an evacuation warning, with residents urged to prepare for an order to get out if required.

Evacuation orders remain in place for Bulga, Broke, Combo, Whittingham, Scotts Flat, Glenridding and Dunnolly.

"Residents and visitors to these areas should take action now to prepare for possible flood impacts," the SES said of Singleton township about 9am on Wednesday.

"Storm and flood impacts may interrupt essential services such as electricity, phones, internet, water and sewerage.

"People in these areas need to closely monitor weather and road closures and make informed decisions early based on individual circumstances.

"Residents should monitor the situation and be prepared to evacuate when instructed to do so. A Flood Evacuation Order will be issued by the NSW SES if and when evacuations are required."

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NSW SES Commissioner Carlene York said the Hunter was the focus for volunteers in NSW on Wednesday, and work had been underway "24/7" to prepare.

"The area we are concerned about today is particularly around Singleton," she said.

"There's an evacuation [warning] out for the Singleton CBD and we're watching what happens with those river rises as the rain falls."

The Singleton branch of the NSW SES at 9am told residents in Broke to get out.

"All Broke community members must comply with the evacuation order," the branch said in a statement.

"If you have a high clearance diesel 4WD you can self evacuate via Cessnock Road.

"If it is not safe to self evacuate please go to Broke Hall where the SES and RFS will assist in evacuating you safely to Cessnock Evacuation centre. Please take all essentials with you."

It comes after what NSW Minister for Emergency Services and Resilience Steph Cooke described as a very difficult night for Hunter residents, with doorknocking in Muswellbrook and Singleton as evacuations began.

NSW Premier Dominic Perrottet said about 85,000 people across the state were subject to evacuation orders or warnings by Wednesday morning, up about 30,000 from Tuesday.

He said Singleton faced "significant risk of flash flooding" on Wesneday.

"Those evacuation orders are there to keep yourself and your family safe," Mr Perrottet said, urging people not to rely on past flood experience to predict what would happen.

"This event is far from over."

Residents at Whittingham, Glenridding, Dunnolly and Scotts Flat were ordered to evacuate by 11pm on Tuesday as floodwaters were expected to pass 11 metres on the Singleton gauge.

"We are monitoring the situation at Singleton this morning, with evacuations likely," the NSW State Emergency Service said in a statement on Wednesday morning.

Evacuation centres have been set up at Cessnock Leagues Club (1 Darwin Street) and Singleton Diggers (8 Dorsman Drive, Singleton Heights).

River levels in several parts of the Hunter are likely to exceed March's flood levels later today, meteorologists warn, with renewed rises as rain keeps falling.

Major flooding is expected to continue at Bulga during Wednesday and Thursday, with further rainfall expected to keep Hunter waterways rising.

At Wollombi the brook peaked at 14.2 metres about 1am Wednesday and is slowly falling, but the Bureau of Meteorology warned it may hit 14.4 metres later in the day due to ongoing rain.

"The heaviest rainfall has cleared the Hunter Catchment, however further rainfall is forecast for Wednesday, which may cause further river level rises and prolonged flooding," the Bureau of Meteorology said in a Wednesday morning weather alert.

"This situation is being closely monitored, and revised predictions will be provided as necessary."

At Singleton, the bureau warns the Hunter river is likely to exceed 13 metres late on Wednesday morning and could reach 13.8 metres by the afternoon, with major flooding.

At Maitland, the river may hit the 8.9-metre moderate flood level in the afternoon.

Singleton mayor Sue Moore on Wednesday urged people to listen to the SES and avoid unneccessary travel.

"To everyone directly impacted by this event, the thoughts of our entire community are with you," Cr Moore said.

"What's so special about our community is the way we all support each other when times are tough, and we will band together to rebuild and recover.

"I stress that we all have a role to play in ensuring our own safety. Please, please do not enter flood water, including in your vehicle. It can be deeper than you think, contain harmful material and conceal damaged or missing parts of roads.

"If you need assistance, please contact the SES on 132 500 or if your life is at risk, call Triple Zero (000) immediately."

The risk at Singleton follows overnight evacuations at Bulga and Broke for residents along the Wollombi Brook, where the tavern was inundated as the waters rose on Tuesday.

The inundation at Bulga was the highest level since 1952, according to the State Emergency Service.

Mr Perrottet said there had been about 1000 requests for assistance since 8pm on Tuesday, and 21 flood rescues overnight.

Payments of $1000 per adult will be made available to those from the affected local government areas from 2pm tomorrow, leaders have announced.

Those areas so far include Cessnock and Central Coast.

A helicopter out of Williamtown will be used primarily for night missions as the flooding continues, Prime Minister Anthony Albanese said.

Elsewhere, a stretch of Cessnock Road that has previously isolated residents of the Maitland suburb of Gillieston Heights has again gone under water.

A Live Traffic NSW map on Wednesday morning showed that the road, in the infamous Testers Hollow area, was cut between its intersections with the New England Highway at Maitland and Avery Lane near Cliftleigh.

Residents on social media on Wednesday who woke to the news made reference to 'Gillieston island', referring to the suburb being cut off from the rest of the community for several days due to flooding in the aftermath of the 2015 super storm.

Problem parts of the river are continuing to rise and more rain has been forecast for the region throughout the day.

The SES has sent additional resources to the Hunter and Central Coast after dangerous weather that troubled Sydney and surrounds for several days began to move north.

According to the BoM, Cessnock recorded more than 86mm of rain between 9am on Tuesday and 7.30am on Wednesday, while Maitland had 68mm, Mangrove Mountain had 60mm, Cooranbong had 64.2mm and Nobbys had more than 53mm.

Singleton Council said its visitor information centre, library, youth venue, OOSH and the Colleen Gale Children's Services facilities were closed until further notice.

The Newcastle Herald reported on Tuesday that the well-known Wollombi Tavern had been flooded and the Bureau of Meteorology was predicting an ultimate flood level in the tourist town about 200mm higher than that of the 2007 Pasha Bulker storm.

State Emergency Services commissioner Carlene York said extra resources were being sent north of Sydney, in line with the forecast movement of the weather.

She urged people to heed orders and advice from the emergency service and called on people to avoid all but essential travel until the dangerous weather passes.

The federal and state governments on Tuesday morning announced a list of 23 local government areas that would be eligible for jointly-funded disaster relief money - including at Cessnock and on the Central Coast.

NSW emergency services and resilience minister Steph Cooke said the funding would provide immediate help to people who have lost or suffered damage to their homes or property during the latest weather event.

There will also be freight subsidies for primary producers, support for councils with clean-up costs and concessional interest rate loans for small businesses, primary producers and non-profit organisations.

"While we are still very much in the emergency response phase of this developing weather event, as waters recede we will work with communities to asses longer term recovery needs and ensure appropriate long-term support is provided," Ms Cooke said.

In life threatening emergencies, call 000 (triple zero) immediately. If you require rescue, assistance to evacuate or other emergency help, ring NSW SES on 132 500.

* Avoid drowning. Stay out of rising water, seek refuge in the highest available place.

* Prevent damage to your vehicle. Move it under cover, away from areas likely to flood.

* Avoid being swept away. Stay out of fast-flowing creeks and storm drains.

* Never drive, ride or walk through flood water. Flood water can be deceptive and dangerous.

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