"Singleton is currently at its peak - around 12.71 metres," a bureau statement said.

"Minor flooding is occurring along the Hunter River at Maitland where river levels are expected to peak below the moderate flood level on Monday morning."

NSW SES directed people to evacuate the "high danger area" in the suburbs of Whittingham, Scotts Flat, Glenridding, Dunolly and Combo, along the Hunter River at Singleton, on Saturday night.

They were evacuated as roads in the area had to close due to flooding.

"Once flood water begins inundating the area, road access, water, sewerage, power, phones and internet may be lost," the SES said.

"If you remain in the area, you will be trapped and it may be too dangerous for SES to rescue you.

"Wherever possible, people should go and stay with family or friends, or make other accommodation arrangements. If you are unable to, an evacuation centre has been set up."

Meanwhile, the rising Hunter River at Maitland attracted plenty of onlookers on Sunday.

The Newcastle Herald reported on Saturday that SES crews had attended at least 10 rescues since heavy rain began on Thursday. Most involved helping drivers who had driven into floodwaters.

The SES said it was lucky no one died, while urging people to stay away from floodwaters.

Two Upper Hunter police officers waded into floodwaters at Wybong on Friday night to rescue a 52-year-old man, who became stranded with his vehicle 400 metres from the road.

Houses were flooded in the Upper Hunter village of Cassilis and Kingdon Ponds in Scone.

As the river rose around Scone, Police and NSW SES crews went door-to-door speaking with residents in preparation for evacuation.

Emergency services then focused their attention on Singleton on Saturday afternoon. The Hunter River rose above 12 metres in Singleton early on Sunday morning and began to peak.

A minor flood warning was issued for the Williams River at Dungog at 5am on Sunday, with minor flooding occurring there.

But the bureau said at 10am that flooding was no longer occurring at Dungog.

"The Williams River at Dungog has fallen below the minor flood level. No further flooding is expected in the Williams River."

River levels along the Upper Hunter River at Denman had fallen below the minor flood level.

Moderate flooding is occurring at Singleton and minor flooding is occurring at Maitland.

The Hunter River at Singleton is currently at 12.71 metres and near its peak with moderate flooding.

The Hunter River at Maitland (Belmore Bridge) may peak at about 8.4 metres on Monday morning with minor flooding.

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 undercover, 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.