Heavy rain and high winds have lashed Perth, leaving 17,000 people without power.
Winds of more than 100kmh hit Perth's coastal areas on Monday morning, dumping rain in squally bursts.
Western Power spokeswoman Marisa Chapman said up to 17,000 households were without power following the storm, mostly in Perth's hills area but extending to the north at Yanchep.
Ms Chapman said power restoration would be delayed as teams had to inspect whole lines before they could turn them on.
The front is the most severe of a series that have descended on WA over the past few days.
A wind gust of 115kmh was recorded at Rottnest Island about 6am today, and the Bureau is warning people to expect winds up to 100kmh with potentially damaging gusts reaching 125kmh this morning.
Alex Krisman from WeatherZone said Cape Naturaliste (109kmh) and Cape Leeuwin (104kmh) also recorded heavy gusts of wind - which coincided with a line of lightning flashes - at the same time as Rottnest Island.
Winds at Perth Airport hit 83kmh while the Perth metropolitan area clocked speeds up to 72kmh at 5.50am.
Rainfall was heavy, particularly across the south west. So far, Bridgetown has had 32mm from 9am yesterday morning - totalling 65mm for the last two days - while 51mm fell on Collie East.
The Perth metro area recorded 23mm from 9am yesterday morning.
Thunderstorms and heavy showers are forecast for today, particularly over the Lower West, South-West and South Coastal districts.
Abnormally high tides are set to cause flooding in low-lying coastal areas.
A gale warning has been issued from Kalbarri right through to the South Australian border.
Surfers are being warned to brace for heavy conditions, which are likely to cause significant beach erosion.
The State Emergency Service has warned people to secure loose objects, move vehicles under cover and stay inside away from windows.
People caught outdoors should find shelter away from trees, powerlines, storm water drains and streams. Boat owners should make sure their boats are securely moored.