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 SES said in a statement on Wednesday morning.

It followed evacuations at Bulga and Broke for residents along the Wollombi Brook, where the tavern was inundated as the waters rose on Tuesday.

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It came as major flooding was taking place at Bulga and Wollombi - the inundation at Bulga the highest level since 1952, according to the State Emergency Service.

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

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 Maitland Mercury 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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