Tree branches and flooding have blocked roads in Perth while a house has lost its roof north-west of the city, with strong winds and heavy rain lashing Western Australia's South West.

Several thousand homes in the metropolitan area were without power late on Wednesday afternoon.

A strong cold front moving across the region has sparked a severe weather warning for people in a line from Jurien Bay to Southern Cross to Esperance, including the Perth metropolitan area.

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A house lost its roof in Bindoon, north-west of Perth, in the stormy weather, the State Emergency Service (SES) said.

The SES said some homes in Belmont and Ascot also lost roof tiles, and said it had received 17 calls for assistance.

Western Power said 9,000 homes were without power in Perth at 5:00pm.

Fallen trees and loose debris have knocked over several powerlines.

The worst affected suburbs include Mount Hawthorn, Glendalough, Beechboro, Brabham and Chidlow.

Earlier, the left lane of the Kwinana Freeway northbound after the Canning Highway was affected by flooding, while in Subiaco tree branches blocked parts of Thomas Street.

The Bureau of Meteorology 9BoM) said a wind gust of 96 kilometres per hour was recorded at Cape Leeuwin at 8:20am, while a gust of 94km/h was recorded at Rottnest almost an hour earlier.

The BoM said the cold front was located from Geraldton to Albany at 1:00pm.

"Severe weather is expected to extend east across the South West Land Division during Wednesday afternoon with the passage of the front and be throughout the warning area by around 5pm," a BoM statement said.

It warned damaging wind gusts of up to 125km an hour may come through the region.

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"The winds will begin to ease in western parts of the warning area overnight Wednesday," the BoM said.

Meanwhile people on the coast are being told to stay out of the ocean as higher than normal tides and dangerous surf conditions will affect the warning area north of Cape Naturaliste.

Flash flooding is also possible.

According to the bureau, people in the southwest of WA experience a front as windy as this about five times a year.

The Department of Fire and Emergency Services (DFES) has urged homeowners to store or weigh down outdoor furniture and other loose objects and ensure pets and animals are safe.

Vehicles should also be moved under cover and boats securely moored, while campers should find shelter away from trees, power lines and water, DFES said.