Lucky escape for pair as tree falls on car amid WA wild weather

Parts of Perth were flooded this morning, including The Oarhouse cafe on the banks of the Swan River in Bayswater. (Facebook: The Oarhouse)

A man has been taken to hospital after a tree fell on the car he was travelling in on a major highway in WA's South West.

Southern parts of the state, including Perth, are being warned a rare storm will bring potentially destructive winds of 125 kilometres per hour on Sunday evening and early Monday.

Conditions are expected to ease along the west coast on Monday morning.

A man and a woman, aged in their 70s, have had a lucky escape after a tree fell onto their car on a major highway in the state's South West this afternoon, as strong winds lashed the region.

The tree is believed to have fallen onto the hood of the car as it travelled along Bussell Highway, where the speed limit is 110 kilometres per hour, near the intersection with Roy Road in Metricup around 1:30pm.

The car was towed away after the incident. (ABC South West WA: Anthony Pancia)

Police said the man was taken to Busselton Health Campus with minor injuries.

Emergency services say one person had to be freed from the car. (ABC South West WA: Anthony Pancia)

It comes as Perth and parts of Western Australia's south brace for "rarely experienced" destructive weather conditions as a severe storm intensifies on Sunday evening.

With a strength only seen every three to five years, the Bureau of Meteorology (BOM) has warned the deep low pressure system is likely to produce wind gusts in excess of 125 kilometres per hour south-west of a line from Lancelin to Albany, including Perth.

"The showers that come through, they're heavy but they move through really quickly, so the main threat to the WA community is the wind."

A fallen powerline in the southern Perth suburb of Beaconsfield. (Facebook: Sandy Armstrong)

The Department of Fire and Emergency Services has issued a warning for people to take shelter.

"Rarely experienced winds may bring down trees, branches and powerlines and loose items or debris may become airborne," the warning said.

Despite the forecast, the AFL match between the West Coast Eagles and Essendon is set to go ahead at Perth Stadium at 5:20pm.

Southern parts of WA, including Perth, experienced wild weather overnight as a cold front crossed the west coast, leaving thousands of homes without power.

The Department of Fire and Emergency Services received 356 calls for assistance, with most coming from Perth for fallen trees, roof damage and water ingress.

Members of the SES removing fallen trees in Rivervale. (ABC News: Lauren Smith