Millions of people have been urged to batten down ahead of a rare monster storm expected to smash coastal communities across a vast area.
Destructive winds, massive waves and torrential rain are forecast for Western Australia's southwest across the weekend, the Bureau of Meteorology says.
"This winter system is unusually strong," meteorologist James Ashley told reporters on Friday.
"It's the type of system we don't see very often ... (and) it's likely to be the strongest winter system we see this year, and may be the sort of system we only see every four or five years."
The storm is expected to impact communities from Geraldton to Albany, along 1200km of coastline.
Destructive winds gusts of 125km/h or more, 50mm of rainfall, flooding in low-lying areas and beach erosion are possible.
"The system will whip up the ocean with waves reaching up to eight meters offshore," Mr Ashley said.
"Those really strong winds will stretch across a large chunk of the southern half of the state."
Tornadoes and damaging thunderstorms that spawn microbursts are also possible.
The wild weather will start on Saturday afternoon and is likely to continue until Monday, with peaks on Saturday and Sunday nights.
Residents have been urged to prepare their properties and travellers have been told to take caution.
"Ensure loose objects such as tarpons, bins, patio furniture, and even sheds are actually locked down so they do not become airborne," Department of Emergency Services Assistant Commissioner Paul Carr said.
"Make sure that you have your emergency kits ready, charge up all your devices before the weather comes in, get a battery-operated radio."
