Up to nine homes at Cassilis and one in Murrurundi in New South Wales' Upper Hunter have been inundated by floodwaters, while the New England Highway between Scone and Aberdeen sits waterlogged.
A major flood warning has been issued for Kingdon Ponds in the Hunter River catchment at Scone, with the local council advising that the river has broken its banks.
"Local residents are advised to take care and move to higher ground," Upper Hunter Shire Council said in a statement.
"The river is at 3.74 metres and still rising. Major flood is predicted."
The New England Highway, one of NSW's major freight highways, is drenched between Scone and Aberdeen with stop-slow traffic controls in place to divert traffic around floodwaters.
"Do follow instructions and guidance of traffic crews and emergency services in the area", the Transport Management Centre's Alf Paranihi said.
"Our advice to any motorists travelling further north from Scone and also to Willow Tree is to exercise extreme caution and allow plenty of extra travel time."
Up to 50 millimetres of rain fell in Cassilis overnight, causing rapid rises on the Munmurra River.
For local Matthew Dean, it was a shock to see flood waters surge quickly into his home.
"At about 3am last night I woke up and there was a lot of lightning. I could hear the rain, and I could hear the river," he said.
"I got a call about two hours later from next door telling me to check my backyard ... and within about five minutes it was at the back doorstep.
Mr Dean said the flood impacted and receded quickly, leaving mud and sludge through his home.
"I haven't experienced anything like that before.
"It was definitely something I hope I don't have to experience again."
Hunter Valley Police Chief Inspector Guy Guiana said the home of the town's sole officer had been impacted.
"The locals have got everybody together and [are] keeping everybody fed and [providing] water at the hall and at the pub," he said.
The heavy rainfall across the Hunter has prompted eight rescues and 55 calls for assistance from local SES crews.
Superintendent Graham Craig from the Hunter State Emergency Service branch says waterlogged roads are proving to be problematic.
"It's usually going to be a case of people going into the floodwater, whether by deliberate act of driving in or by accident."
Superintendent Craig says one call for help was made by a Murrurundi local at their home.
"A resident has actually experienced water coming through their house, and that has been looked after by our Upper Hunter command.
"It is flash flooding; it's not riverine flooding that's causing this problem.
"It's the runoff, so it is important that people be very vigilant and aware of what's going on with the weather that's around."
In the nearby town of Merriwa, local resident Cassandra McLaren says it is the biggest flood she's seen in 30 years.
"One of the biggest floods; we've never seen anything as high as that, just water everywhere," she said.
Several school bus routes in the Upper Hunter have been impacted.
The Golden Highway at Whittingham is also closed, and several other minor roads are closed in the region.
© ABC 2021
13:38 AEDT A 75-year-old cattle farmer used a jet ski to stage a heroic rescue of a woman stuck in fast-moving floodwaters near the Queensland town of Dalby.