Major flooding is expected around parts of the Hunter Valley after 200 millimetres of rain lashed the region.
The Paterson River is expected to peak around 13 metres at Paterson, isolating the rural town.
Floodwaters are expected to fall just short of inundating homes in Dungog this morning, when the Williams River peaks around 8.5 metres.
The Hunter River is expected to peak around five metres, which is below the minor flood level.
Conditions are expected to ease from midday as the rain moves further north.
The State Emergency Service has now had 193 calls for assistance, with just 14 outstanding this morning.
Most have been around Newcastle and Lake Macquarie for help with fallen trees and roof damage.
Hunter Region Controller Greg Perry says Paterson could be isolated for much of the day, but it is hard to tell with the rain still falling.
"The Bureau tell us that 187 millimetres of rain has fallen during the past 33 hours up until 3am this morning," he said.
"So even the Bureau have basically said it's not possible to predict the flood peaks because of uncertainty over how much more rain will fall, so it's been pretty constant overnight with some reasonable heavy falls."
He said Tocal Road is likely to be shut from mid morning.
"That'll be a bit of an inconvenience there for some period of time," he said.
"The Williams River at Dungog should peak around 8.5 metres this morning."
"There was some concern that it might have got a bit higher than that and into some premises, but it will come reasonably close to the back of some people's houses up there but we don't expect there will be any over floor inundation."
© ABC 2013
16:12 EDT For one farmer in southern New South Wales the exceptional conditions has him thinking that Christmas is coming early.