Rescuers on Sunday morning will resume searching for a woman swept away in floodwaters overnight in the NSW Hunter region.
NSW police said a car had attempted to drive through floodwater and became stuck - the driver, a 27-year-old woman, escaped unharmed but a female passenger was swept away.
Tens of thousands in NSW spent a night without power as heavy rain, floods and unprecedented snow wreaked havoc.
Between 50 and 100mm of rain drenched parts of NSW's Mid North Coast and northern Hunter, on Saturday.
The NSW State Emergency Service responded to 745 incidents across 24 hours.
The SES managed to rescue a 40-year-old man stuck in a tree who was later swept into Black Creek, 16km north of Cessnock. He was taken to a hospital for a medical check.
A new low-pressure system is expected to push up the NSW coast on Sunday, but conditions are likely to ease by afternoon, the bureau said.
The bureau upgraded its warning for major flooding in Tamworth and Gunnedah as the Peel and Namoi rivers rose.
Residents in parts of Scone were warned to evacuate by 4am AEST amid a major flood threat.
The NSW SES urged residents at the Ferndale Caravan Park, north of Newcastle, to prepare to evacuate because of potential flooding from increased flows from Chichester Dam into the Williams River.
The Bureau of Meteorology has issued a severe weather warning, as a cold front moves through WA on Sunday, with damaging winds expected across the state's south west, including Perth, Albany, Bunbury, Margaret River and the goldfields.
"Most of these damaging wind gusts will be driven by showers and thunderstorms," meteorologist Miriam Bradbury said.
Authorities warn surfers, fishers, swimmers and boating enthusiasts to stay clear of the coast amid dangerous swells.
Snow fell at depths not previously seen at Armidale and Guyra in the NSW Northern Tablelands on Saturday.
The SES responded to more than 100 vehicles stuck in the snow on the New England highway and other roads in the area.
More than 27,500 NSW homes and businesses experienced power disruptions overnight, Essential Energy said.
People have been urged to stay at least eight metres away from fallen power lines, power poles and damaged electricity equipment.
Lightning temporarily forced the Wallabies and British and Irish Lions to seek cover during Saturday night's clash in Sydney, before the Australians managed to avoid a series whitewash.
Much of the match was played in torrential rain, while lightning early in the second half forced a rare 38-minute stoppage as several hundred fans were forced to evacuate the stadium to take shelter.
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