The strong winds and drenching rain are not set to let up, with storms and showers forecast into Wednesday night.
The Department of Fire and Emergency Services said a developing strong cold front and low pressure system is likely to produce severe weather conditions across southwest WA Wednesday afternoon through to early Thursday morning.
After the passage of the cold front, squally conditions are expected to continue between Bunbury and Jurien Bay, including Perth, through until early Thursday morning.
Warnnings for residents and motorists are in effect, as wind speeds may reach in excess of 100km/h in some areas.
Thunderstorms and hail are also expected to arrive with the front.
The Department of Fire and Emergency Services advises that people should:
* If outside find safe shelter away from trees, power lines, storm water drains and streams.
* Close your curtains and blinds, and stay inside away from windows.
* Unplug electrical appliances and do not use land line telephones if there is lightning.
* If boating, swimming or surfing leave the water.
* Be alert and watch for hazards on the road such as fallen power lines and loose debris.
* Keep away from flooded drains, rivers, streams and waterways.
* Be careful of fallen trees, damaged buildings and debris.
* Be careful of fallen power lines. They are dangerous and should always be treated as live.
* Assess your home, car and property for damage.
* If damage has occurred take photos and contact your insurance company to organise permanent repairs.
* If your home or property has significant damage, like a badly damaged roof or flooding, call the SES on 132 500.