In Forbes, where the waters had largely receded, residents are waiting to hear from State Emergency Service assessors if they can return to their homes.

Meanwhile, the immediate emergency response is now focused on Condobolin where floodwaters peaked at 7.59 metres on Sunday and remain steady at around 7.57 metres, with major flooding on Monday afternoon.

As the flood peak made its way downstream along the Lachlan River, residents of Deniliquin were told they would have to evacuate by Wednesday.

Making matters worse, widespread strong to damaging winds above 90km/h buffeted much of Australia's southeast throughout Monday.

"Winds will ease from the west into tonight, but the risk of damaging winds may persist across elevated parts of Victoria and NSW into Tuesday morning," the Bureau of Meteorology said in a statement.

"Due to ground saturation, the risks of trees and powerlines toppling are elevated."

Authorities are keeping a close eye on a three-kilometre temporary levee surrounding Condobolin's CBD, which SES chief superintendent Dallas Burns says is expected to hold.

As floodwaters recede in Forbes, the town is transitioning to the recovery stage with Emergency Services Minister Steph Cooke saying damage assessments are being conducted, with the aim of allowing some people to return home.

ADF troops are helping with sandbagging and the cleaning out of homes, although some parts of the town remain waterlogged.

"More than 1000 damage assessments have been undertaken in Forbes, where more than half have experienced some level of damage," SES assistant commissioner Sean Kearns said.

"We have NSW SES crews continuing to assist communities downstream of floodwaters on the Lachlan River at Euabalong and the Edward River at Deniliquin with sandbagging, resupply and evacuation assistance."

Flood rescue operators from Singapore are helping in Deniliquin and communities along the Lachlan River.

As the peak moves downstream, Ms Cooke says already isolated communities are bracing for severe water level rises.

"Our thoughts are with those communities," she said.

"We know that you're going through a hard time and will continue to stand with you throughout the response and the recovery phase."

To support communities, nine recovery assistance points were opened this week including in Eugowra, Orange, Parkes, Gunnedah, Cudal, Wagga Wagga, Narrabri and Moree.

The multi-agency hubs are designed to help flood-impacted individuals, families, farmers and business owners begin the clean-up, recovery and rebuilding process.

In the 24 hours until Monday afternoon, the SES received 657 calls for help, and conducted two flood rescues.

There are 102 warnings in place in the state, 17 of which are at emergency level.

Many of the calls for help came from across Sydney and the Illawarra where wind gusts of up to 100km/h saw trees uprooted, roofs blown off and powerlines downed.

"With winds as strong as they are today we are asking residents to move their cars from beneath trees and to secure items in their yards and businesses which could become airborne, including trampolines or sheet metal" Mr Kearns said.

"Residents can prepare for winds by removing tree branches over buildings, and ensuring roofing is in good order".

Australian Associated Press