A tropical cyclone has begun crossing the coast near Western Australia's Pilbara region, bringing very destructive winds of more than 200 km/h.

The Bureau of Meteorology has confirmed Severe Tropical Cyclone Damien has reached the coast near Dampier, with its effects being felt at the industrial port and the nearby city of Karratha.

The category three cyclone is causing gusts of up to 220 km/h near its centre.

The worst of the winds won't pass the area until the tail end of the cyclone moves through.

When that occurs, debris that has been stripped by the front end of the cyclone could be thrown around, the BOM's Neil Bennett said.

"Getting into fading light, it's particularly dangerous and a very hazardous environment to be out and about in," he told reporters in Perth on Saturday.

Damien is heading south-to-southeast steadily at a rate of about 13 km/h.

It is forecast to hit De Grey to Onslow, including Port Hedland, Pannawonica, Barrow Island and extend to Tom Price and Paraburdoo.

Residents between Dampier and Whim Creek have been warned of the potential for a very dangerous storm tide.

Heavy rain is also expected to cause flooding in the Pilbara and Gascoyne regions, with falls of up to 300mm or more possible in some areas.

A "red alert" is an effect for people in or near People in or near Whim Creek to Mardie and south to Pannawonica, with residents told to seek shelter immediately.

Department of Fire and Emergency Services WA Assistant Commissioner Metropolitan Brad Delavale said the alert is likely to remain in place all night and urged the community to heed the warning.

"The warning is quite clear, so I ask the community to abide by those warnings, to stay indoors," Mr Delavale said.

"We have emergency personnel to deploy for assistance however that is for emergency situations, not for people who are just taking it on themselves to venture out."

There have already been reports of power losses in affected areas, the assistant commissioner said.

The cyclone is expected to drop to category two sometime after midnight, before its winds weaken and lose cyclone status on Monday.

Perth is not expected to be impacted by Damien.

This is the third cyclone of the season off the WA coast.