One of the year's strongest cold fronts is bearing down on Perth and the south-west of the state today, as residents have been urged to secure their homes and prepare for gale-force winds.

The deep low pressure system is expected to bring a cold unstable air mass over the South West Land Division.

It is the first major system for the cool season this year and the kind of weather only seen once or twice a year, according to the Bureau of Meteorology (BOM).

The BOM has forecast it will bring very strong winds with gusts up to 125 kilometres per hour, hail and rain to the south-west of Western Australia.

Widespread damaging winds are expected to develop in western parts of the warning area from late Tuesday afternoon and extend to remaining parts of the warning area by Tuesday evening.

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Take this seriously, prepare your house

BOM duty forecaster Darryl Bink said people should "absolutely" take the storm warning seriously.

"You've got wind gusts exceeding 90kph, so any loose-lying material, clean it up around your yard and around the area, and make sure your windows are secured," he said.

Mr Bink said the BOM was expecting light showers ahead of the front today followed by isolated thunderstorms, with the strongest and most damaging winds coming through in the late afternoon and early evening about 6:00pm or 7:00pm.

"This front is expected to be windier than a typical cold front and is likely to produce the kind of weather that is only seen in south-west WA about two times per year," the bureau said in a statement.

There is a gale warning in place for waters from Geraldton down to Esperance.

The Department of Fire and Emergency Services advises people should:

• If outside find safe shelter away from trees, power lines, storm water drains and streams.
• Close your curtains and blinds, and stay inside away from windows.
• Unplug electrical appliances and do not use landline telephones if there is lightning.
• If boating, swimming or surfing leave the water.
• Be alert and watch for hazards on the road, such as fallen power lines and loose debris.
• Keep away from flooded drains, rivers, streams and waterways.
• Be careful of fallen trees, damaged buildings and debris.
• Be careful of fallen power lines — they are dangerous and should always be treated as live.
• Assess your home, car and property for damage.
• If damage has occurred, take photos and contact your insurance company to organise permanent repairs.
• If your home or property has significant damage, like a badly damaged roof or flooding, call the State Emergency Service on 132 500.

Mr Bink said the system would move through fairly quickly.

"It does clean up fairly quickly, so going into Thursday we'll just see a ridge of high pressure extend into southern parts of the state," he said.

"[There is] still the chance of a few showers around on Thursday through mainly coastal parts, on Friday a ridge builds further through southern parts, so basically a partly cloudy day, but a generally fine weekend."

Yesterday's storm dumped 13.6 millimetres of rain on Perth in a 24-hour period.