Seroja hit the coast south of Kalbarri at about 8pm AWST on Sunday as a category three system and was moving inland north of Geraldton.

The storm is travelling at about 55km/h and significant impacts are expected to extend inland through to Wheat Belt communities overnight, the Bureau of Meterology said.

The BOM said wind gusts of up to 170km/h were recorded near Kalbarri as the storm made landfall.

Reports of power outages in Geraldton and property damage in Kalbarri started trickling in as the storm's force was felt.

Residents across WA's mid west were told to take shelter during what their premier described as a cyclone "like nothing we have seen before in decades".

There was a "red alert" in place across an 800km stretch of coastline south of Carnarvon to Lancelin.

Communities included in the zone were Geraldton, the shires of Carnamah, Coorow, Chapman Valley, Dandaragan, Irwin, Mingenew, Morawa, Northampton, Perenjori, Shark Bay and Three Springs.

Evacuation centres are open in Port Denison, Carnarvon and Denham.

Carnarvon's historic One Mile Jetty was one of the first casualties of the cyclone, reportedly ripped apart around lunchtime on Sunday.

Seroja will continue to impact the area until midnight, with each community expected to experience the worst of the weather for about three hours, the Bureau of Meteorology's James Ashley said.

Gales, destructive winds, high tides, heavy rainfall, flash flooding, dangerous surf and beach erosion are among the dangers.

The WA Country Health Service said Geraldton Hospital will continue to treat emergency patients during the cyclone, but all other appointments have been or will be cancelled.

The Bureau of Meteorology issued a flood watch for the Wooramel, Murchison, Greenough,Yarra Yarra Lakes, Moore, Hill and parts of the Salt Lake District and Avon River catchments.

A severe weather warning was also issued for Monday for parts of the Greater Perth, Goldfields-Midlands, Great Southern, and Midwest-Gascoyne regions.

"If you live in South East Coastal and parts of Goldfields, Eucla, Great Southern and Central Wheat Belt districts you need to get ready now for the severe weather coming tomorrow," emergency warnings said.

"This is a rare weather event for people in southern and eastern parts of Western Australia."

Australian Associated Press