Flooding and thunderstorms are continuing across inland areas of New South Wales, with the wet weather not expected to clear until Monday afternoon.
Affected areas include the south-west slopes, the Central and Southern Tablelands, the Riverina and ACT.
Pre-positioned aircraft are based in high-risk locations across the state, while a major resupply operation is underway today to provide essential goods to towns in need.
"It spans an area more than 40,000 square kilometres of NSW. To put it into context, that is the size of Switzerland," Minister for Emergency Services and Resilience Steph Cooke said.
"In these communities, we are resupplying food, medicines, animals with fodder. It is ongoing around the clock."
Towns of concern are Wagga Wagga, Albury, Yass, Young, Forbes, Condobolin and others along the Murray River and Murrumbidgee systems.
On Sunday, Young experienced flash flooding after 20 millimetres of rain fell within 30 minutes.
The Barwon catchment and its impact on Brewarrina and Collarenebri is also of concern, while the towns of Louth and Tilpa along the Darling River could move towards a record flood similar to 1976.
Along the Lachlan River, Condobolin and Euabalong may see flooding similar to the June 1952 flood, whilst Hillston is on track to meet the August 1990 flood level.
Power outages also continue to impact large parts of the state, including in far west NSW where 10 power poles were taken out near Nundooka Station, 150 kilometres north of Broken Hill.
The Bureau of Meteorology said the severe weather, potentially including hail, would move from inland areas to the coast.
"The trough and a cold front will combine and begin marching across the state throughout the day and into Monday, and that will extend to the coastline and potentially the Sydney metropolitan area," the Bureau's Steve Bernasconi said.
"We do expect widespread rainfall to occur, around about 38 and 40mm across much of the state, and a very high chance of severe thunderstorms with intense rain, damaging winds and the potential for hail."
However, he said the wet weather would likely ease by Monday afternoon.
"There is a positive side to this, that coming Monday afternoon and into Tuesday and out to Friday, we are looking at a spell of cooler, drier and more settled conditions," he said.
NSW SES Commissioner Carlene York said the next 24 to 36 hours were of concern to volunteers.
She urged residents to remain vigilant and not to drive or walk through floodwaters.
"During the week, we passed 1 million sandbags going out to the community," she said.
"We've ordered another 400,000 to make sure we can meet the ongoing need.
"That shows the community are listening and preparing but regretfully there are some people that aren't."
Water rising quickly
Condobolin residents Mark and Sharlee Haworth noticed floodwaters first started to rise near their property on Friday.
They have been sandbagging their house in preparation for the latest front.
"We've got a levee right around [the property] and it started coming around that pretty quick," Mr Haworth said.
"We thought we'd be right with our bank but it had come around that and rose quickly."
Meanwhile, residents in Forest Hill, an outer suburb of Wagga Wagga, are cleaning up after an intense thunderstorm rolled through on Saturday.
More than 60mm of rain fell within an hour on Saturday afternoon, causing flash flooding and damaging roads and some homes.
Resident Steve Seetanna said it felt like the storm "came out of nowhere".
"I think the rain was coming in sideways at one point, and then we had a break for about five or 10 minutes, and then after that we had torrential rain again with hail," he said.
"It's definitely something we haven't seen before."
The NSW government has approached international counterparts for assistance to deal with the floods affecting the state.
Ms Cook said she was in discussions to seek aid from overseas to ease volunteer fatigue and would provide updates in the "days and weeks ahead".
"We will now turn our attention to reaching out internationally and seeing what support we can ask for from other countries who aren't in the prolonged flooding event that we're experiencing," she said.
"We have a history of doing so in relation to bushfires, we've never had to do it before for floods."
