Perth and the South West are set to be pummelled by "tornado-strength" wind gusts and dangerous swells in "once in five-year" storm.

The Bureau of Meteorology is warning the “deep low” system will begin impacting west-facing towns as far north as Geraldton as of Saturday evening, before moving down the coast…

Perth and the South West are set to be pummelled by "tornado-strength" wind gusts and dangerous swells in "once in five-year" storm.

As the massive storm's set to bare down on parts of WA, the coastal town of Lancelin is tonight on high alert as huge swells threaten to breach its already eroded coastline.

Perth and large parts of the WA coastline are set to be smashed by severe rain and thunderstorms today.

The powerful weather event is being described as a "once in five-year" storm and is bringing winds of up to 125km/ph.

A rare storm event has pummelled Western Australia's south, sending trampolines and sheds flying.

The entire South Australian coastline is under a severe weather warning with rain and damaging winds up to 100km/h on the way.

At its peak, the storm wiped out power to 160,000 households.

The low-pressure system, which on Monday was tracking south-east, upended trees, downed power lines and turned roads into rivers.