The powerful weather event, typically seen only once every five years, could bring wind gusts of up to 125km/h to Perth and communities along Western Australia's coast.
Images of widespread destruction have flooded social media, including one showing a shed seemingly tossed into a swimming pool in Mandurah on the southwest coast.
There were widespread power outages in multiple parts of Perth and its surrounds, with about 10,000 customers affected state-wide, according to Western Power.
Most were expected to have their electricity restored by mid-afternoon.
Wind gusts of 107km/h were recorded at Busselton Jetty in the morning, while 102km/h gusts were recorded at Rottnest Island.
Residents had been urged to close their curtains and remain inside away from windows as the low-pressure system approached the state's southwest in the morning.
"People should definitely tie down loose items like outdoor furniture and trampolines," Bureau of Meteorology duty forecaster Luke Huntington told AAP.
"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.
"This situation definitely doesn't happen every year and the wind is going to be the worst hazard," Mr Huntington said.
A major police search earlier wrapped up when an 11-year-old autistic, non-verbal boy was found safe after going missing overnight in Perth's western suburbs during the wild weather.
The boy had been missing for almost eight hours, prompting a large-scale search involving police and State Emergency Service volunteers on foot and horseback.
Police on Sunday hailed the "great news" the boy had been found safe and well, and reunited with his family.
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.Â
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