The weather event, seen only once every five years, could bring wind gusts of up to 125km/h to Perth and communities along Western Australia's coast.
"This situation definitely doesn't happen every year and the wind is going to be the worst hazard," Bureau of Meteorology duty forecaster Luke Huntington told AAP.
Residents have been urged to close their curtains and remain inside away from windows as the low-pressure system approaches the state's southwest on Sunday morning.
"People should definitely tie down loose items like outdoor furniture and trampolines," Mr Huntington said.
"When those strong winds are coming through, make sure you stay inside and just stay off the roads, in case of fallen power lines or trees."
Perth is expected to be lashed by strong winds on Sunday afternoon, with destructive gusts of up to 125km/h forecast across the southwest from Lancelin to Albany, including the city, through to the evening.
The system has been battering the coastline since Saturday evening.
The threat of heavy rainfall has eased after widespread rain swept across parts of the state, with Ludlow, about 200km south of Perth, recording more than 43mm of rainfall in two hours on Saturday night.
Damaging surf conditions are set to continue with abnormally high tides.
Locations affected include Albany, Bunbury, Esperance, Katanning, Mandurah, Manjimup, Margaret River and Perth.
The low-pressure system is expected to move east, with the risk of damaging winds shifting towards southeast Western Australia on Monday.
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