Thirty-five thousand residents have been left isolated after another major flood took hold this week - the second in just four months.

On Thursday afternoon the NSW State Emergency Service (SES) out a text message alert warning of significant rises in the Hunter River.

Residents in Oakhampton, Lorn and Bolwarra areas are likely to become isolated and must be prepared.

Rural property owners in these areas are also being warned to move livestock and machinery to higher ground.

Everyone in these areas is urged to monitor the conditions and act early if they are at risk of flooding.

The city was smashed with 285 millimetres of rain at Maitland Airport this week - 123 millimetres more than the July monthly average - while the Belmore Bridge saw its average monthly rainfall of 130 millimetres fall in a single day. The gauge there has now received 255 millimetres in just four days.

Meanwhile, in Paterson, 240 millimetres fell - beating its July monthly average by 208 millimetres in just 96 hours.

Several suburbs remain isolated including Gillieston Heights, Cliftleigh and Hinton. Flood boats are operating in these areas to bring in supplies and transport people for essential work, medical appointments and in emergencies.

Upstream, Wollombi, Bulga and Broke - which are among the worst hit areas - are still isolated after significant flooding. This week Bulga saw its highest flood height since 1952.

The NSW SES warned on Thursday that the Hunter River at Maitland could reach as high as 10.5 metres before it peaked. The river peaked at 13.7 metres in Singleton on Wednesday night, which exceeded the March 2022 flood level.

Maitland Railway Station had to be protected with flood gates and sandbags to stop it from being inundated. Meanwhile, the rally ground filled with water and the highway was cut between the overpass and the old Maitland Hospital roundabout.

The amount of flash flooding across the city forced the Slow Food Earth Market Maitland in The Levee to be cancelled on Thursday morning. At that time a lot of the producers were isolated in their own communities.

The Bureau of Meteorology has confirmed there is no significant rainfall forecasted for the region for the next week, but, a spokeswoman said July was predicted to be wetter than average so she couldn't rule out more wet weather before the end of the month.

A NSW SES spokesman urged the community to remain on alert as conditions could change quickly.

"This a live situation with flood heights varying depending on the specific locations along the Hunter River. We ask that communities remain vigilant and keep up to date with SES warnings and orders, and Bureau of Meteorology advice," he said.

Maitland is yet to receive a Disaster Declaration, which unlocks a range of payments to support affected communities.

Maitland MP Jenny Aitchison has started pushing for it with a letter to the relevant state and federal government ministers.

She has shared the "very specific and unique details" that the community is experiencing.

"I have also been in contact with the Deputy Premier's Office and the Minister for Emergency Services and Resilience NSW," she said.

Flash flooding around the town won't be able to drain into the river system until the river level falls enough for the flood gates to reopen.

There are more than 60,000 people affected by the floods across NSW and there are 74 evacuation orders in place, including for Millers Forest and Duckenfield.

Those residents were told to move to higher ground on Wednesday night, amid fears of further flash flooding and river rises.

With more rain falling in the upper catchments of the Paterson and the Williams rivers on Wednesday, the floodwater is expected to hang around in the region for several days.

The water in the Paterson River will be backed up by the swollen Hunter River, which must subside first in order to let the water in the Paterson flow into it.

Major flooding in the Wollombi Brook, and at Bulga, is expected to keep townships downstream isolated for several days before the water completely subsides. It is anticipated townships like Hinton will be cut off for at least a week.

If you require assistance from the SES phone 132 500. In an emergency, phone Triple Zero.

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