Wild weather lashes Perth and WA's South West as BOM warns of ...

Severe weather is lashing large parts of Western Australia, as strong winds and heavy rain cause damage and disruption across Perth and the south west of the state.

Key points:Widespread damage has been recorded across Perth and the South WestA wind gust of 128 kph was recorded on Rottnest IslandMore severe weather is expected on Wednesday afternoon

The worst affected areas are in the state's south, with Busselton Airport recording 91 millimetres of rain, and Pemberton further inland recording 50 millimetres.

Suburbs across Perth have also experienced heavy downpours and strong winds.

At Floreat Forum shopping centre, rain was seen streaming from the roof inside the shopping centre.

Staff ran to contain the spread and set up signs alerting customers as water streamed from the ceiling.

Department of Fire and Emergency Services (DFES) assistant commissioner Peter Sutton said there have been 80 calls for assistance so far, with more expected.

"The majority of the requests are for roof tiles being blown off, requiring tarping, and water coming through windows and light fixtures," he told ABC Radio Perth.

"But also we've had a number of fallen trees and fences falling blocking driveways."

Thunderstorm warning cancelled

Earlier the Bureau of Meteorology warned "very dangerous" thunderstorms would hit across greater Perth but at 9:48am said the thunderstorms were no longer occurring and cancelled severe weather warnings in the metropolitan area.

This postie had to battle through the rain on Wednesday morning. (ABC News: Jake Sturmer)

A severe thunderstorm warning for the lower west and south west districts has also been cancelled.

However, it said a severe weather warning for damaging to locally destructive winds remained current over WA's south west, and further severe thunderstorm warnings could be issued.

Perth was lashed by wet weather on Wednesday morning.(ABC News: Jake Sturmer)

The wind warning stretches across a huge swathe of the state, from Esperance in the south east to Kalbarri in the north and including most of the Wheatbelt and part of the Goldfields.

The storm front measures almost 800 km wide, or about the size of New South Wales.

This Bunbury kite surfer went out in conditions not for the faint-hearted. (ABC News: Amelia Searson)

The kitesurfer got airtime as the strong winds lifted him above the water.(ABC South West: Amelia Searson)

"Isolated more intense thunderstorms are possible, particularly about the coast and nearby inland areas, posing a risk for locally destructive wind gusts above 125 kph, including the greater Perth area," BOM said in its warning.

BOM said such weather systems typically only occur twice a year. 

Perth has been lashed by heavy rain as a cold front crosses a large part of the state. (ABC News: Jake Sturmer)

More than 20,000 households across the state were reported to be without power at the peak of the storm, including at least 4,000 people in the Bicton, Palmyra, Attadale and Fremantle areas.

Crews reported an emergency outage, with a tree falling onto power lines, leaving 4,269 customers without electricity.

A tree blocking a road in Atwell, in Perth's southern suburbs.(Supplied: Ashlee Sommers)

Another 4,000 were reported to be without power in Wellard, Calista, Medina, Parmelia, Kwinana and Leda.

Flooding and debris from fallen trees is causing havoc on the roads, with Main Roads issuing warnings for motorists to exercise extreme caution at several locations across the metropolitan area.

Damage was reported at a home under construction in Scarborough.(Supplied: Dennis Schenk )

Busselton flooding closes roads

The City of Busselton said heavy rainfall had flooded the roundabout outside of Aldi on West Street, creating a traffic hazard.

The Department of Fire and Emergency Services said it received several calls for assistance for minor damage to properties in Busselton.This included ceiling leaks and damage to roof tiles.

A wind gust of 128 kph was recorded at Rottnest Island at 9am while 113 kph was recorded at Garden Island at 9:11am.

On the mainland, a 93 kph gust was recorded at Perth Airport around the same time.

Perth has been hit by strong winds and heavy rain as a cold front moves over the south west of Western Australia. (ABC News: Jake Sturmer)

Fallen tree blocks highway

Meanwhile, a tree fell over the road on Forrest Highway two kilometres north of Riverdale Road in Myalup, blocking the southbound lane.

The severe weather forced the closure of Busselton Jetty, including the underwater observatory and train.

Peel Terrace in Busselton was inundated with water.(ABC News: Georgia Loney)

The Bureau has told ABC Radio Perth the rain is likely to continue into Wednesday afternoon.

"We've seen more than 90 millimetres [of rain] through the Busselton area," forecaster Angeline Prasad said.

Busselton's famous 1.84km long jetty was shut due to "extreme weather".(Supplied: City of Busselton)

"This heavy fall area has shifted northwards as this front approaches. So we're likely to see some heavy falls that may lead to flash flooding through the Bunbury area and inland areas."

This playground in Busselton was swamped as wild storms and heavy rain hit the area. (Supplied: Hugh Gray)

The Bureau said the front was expected to be windier than normal, and they  anticipated locally destructive wind gusts of up to 125 kilometres per hour.

As a result of the predicted strong winds, the fire danger was elevated across inland areas.

Lacey Filipich reported her ceiling collapsing at her home.(Supplied: Lacey Filipich)

"The damaging wind risk will gradually diminish about the west coast during the afternoon," BOM said.

Conditions are expected to ease quickly on Thursday, with mild conditions expected in coming days. 

A humid morning in Kalgoorlie as the severe weather moves inland to the Goldfields.(ABC News: Robert Koenig-Luck)