One man is dead and a woman is in a critical condition after their car was crushed by a tree toppled by fierce winds.
Emergency services worked to free the pair in western Victoria's Gellibrand on Wednesday afternoon, but the male driver died at the scene.
The female passenger has been airlifted to hospital in a critical condition.
The operation was one of more than a 1000 emergency call-outs across multiple states as wild weather wreaks havoc across southern Australia.
"SES volunteers have been working tirelessly with other emergency services and local councils to make sure that we can get those trees off the roads and off people's buildings and properties," chief operations officer Tim Wiebusch told reporters in Melbourne on Wednesday.
Conditions are expected to ease on Wednesday night, but experts warn winter gales could persist into early spring.
In Victoria, State Emergency Service volunteers responded to more than 1000 calls for assistance in the past 24 hours, with 800 of those related to fallen trees.
Severe warnings are also in place for parts of WA, NSW and Tasmania, where emergency services responded to 44 requests overnight.
Mr Wiebusch urged the community to be patient, as call-outs were expected to continue into the night and coming days.
The SES said the damage was concentrated to Victoria's southeast and parts of Melbourne.
Abnormally high tides and dangerous surf was expected to continue around the southwest coast, Gippsland and Port Phillip Bay, potentially flooding surf beach car parks.
In NSW, emergency services reported damaging gusts of more than 110km/h, with the Illawarra, South Coast, Snowy Mountains, Blue Mountains and parts of Sydney affected.
SES crews had responded to 535 incidents across the state by 3pm, with the Illawarra and metropolitan Sydney most affected.
The NSW Rural Fire Service said it was responding to 27 fires statewide.
The wild weather has continued in the nation's west, with WA's Department of Fire and Emergency Services issuing a Prepare Now alert for parts of the south and southwest coast.
In Victoria, wind gusts of 135km/h were recorded in Wilsons Promontory on Victoria's southeast tip, and gusts of 128km/h at Mount Buller.
Conditions were expected to ease temporarily on Wednesday night, Bureau of Meteorology senior meteorologist Kevin Parkin said.
"There is a risk on Monday, with a low pressure system tracking across Tasmania ... which could result in similar gusts that we're seeing today," Mr Parkin told reporters.
"These winter gales are going to continue."
Victoria's two biggest electricity distributors Powercor and AusNet told AAP they were working to restore electricity to about 15,000 customers.
