'Rare event': Once in a decade superstorm smashes Australia

A devastating, “once in a decade” storm has lashed Western Australia and will continue to wreak havoc across large parts of the state on Monday.

High winds and heavy rain battered most of the state in a "rare event" that has damaged homes and businesses and cut power to tens of thousands of properties.

It’s being labelled WA's wildest autumn weather in years, as the remnants of ex-tropical cyclone Mangga collide with a cold front and trough, whipping up gusts of about 100 km/h.

"This is a rare event for Western Australia, particularly due to the extent of the area affected and the possibility of multiple areas of dangerous weather," the Bureau of Meteorology said.

"A similar event to this one occurred in June 2012, which led to over 600 calls for assistance and over 170,000 homes losing power."

BOM’s WA State Manager James Ashley told reporters the storm was a “once in a decade” event.

Significant damage expected

The Department of Fire and Emergency Services warns the "unusual weather" could cause significant damage to homes and make travel dangerous.

Images from a row of shops in Perth’s Bedford reveal part of the damage caused on Sunday with the awning giving way under the conditions.

Strong winds raised dust through large parts of the Gascoyne and Central West areas, blanketing Geraldton.

The strongest gust recorded by 2am was 126km/h at Cape Leeuwin.

High winds blew apart a house in Geraldton, blew off roofs and damaged shops as well as bringing down trees and power lines.

There were also reports of damaged homes and downed trees and power lines in other regional centres and in Perth on Sunday night.

Western Power said in a statement at 5.30pm that about 50,000 customers were experiencing storm outages across the state including around 37,000 homes and businesses in the Perth metropolitan area.

The power company said it had 70 crews addressing hazards on the network but many households should expect to remain without power overnight.

"We will not attempt any repair work during the storm because operating elevated work platforms (cherrypickers) and other equipment is not safe to do so because of the dangerous winds," it said.

Eight-metre waves predicted for Monday

A "take action now" alert is in place for most of the state, including Perth which was expected to get its strongest lashing on Sunday night.

Residents have been warned to unplug electrical appliances, avoid using landline phones if there is lightning, close curtains and blinds, and stay away from windows.

Anyone stuck outside should find safe shelter away from trees, powerlines, storm water drains and streams.

Motorists are warned to watch for hazards, such as debris, and to not drive into water of unknown depth and current.

Residents in coastal areas from as far north as Exmouth and south to Augusta are specifically warned of the potential of a dangerous storm tide.

Peak wave heights in excess of eight metres are predicted for the south west coast on Monday, causing significant beach erosion.

Surfers are being urged to not go in the water.

with AAP

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