Lasting damage has been done by WA's once-in-a-generation storm, turning stretches of Perth beaches into cliff edges.

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.

Western Australia has been battered by a "once-in-a-generation" storm, leaving a path of destruction Geraldton to Albany.

Lasting damage has been done by WA's once-in-a-generation storm, turning stretches of Perth beaches into cliff edges.

Weather alerts have been issued for dangerous high tides and flood risks.