'Too late to leave': cyclone weakens but hazards remain

Residents along the state's coastline are preparing to assess the damage after the storm left a trail of destruction in the Pilbara and North West Cape.

The system continues to lose intensity as it sweeps southeast, bringing gusts up to 100km/h and heavy rainfall.

Emergency warnings have been downgraded across the state, except for an inland area east of Mullewa, about 450km north of Perth.

Isolated watch and act warnings remain in place for parts of Perth, the Mid West and Gascoyne and west of Onslow to Coral Bay.

"Shelter indoors now. It is too late to leave," a warning on the Emergency WA website said.

As of 5am on Saturday, the system was located about 135km northeast of Geraldton.

Damaging wind gusts were still occurring, particularly on the eastern side of the system, with peak gusts up to 120km/h possible through the morning.

Overnight, gusts reached 133km/h at Carnarvon Airport and 122km/h at Gascoyne Junction, while widespread rainfall totals of 70 to 100mm were recorded across the Gascoyne.

Isolated coastal towns bore the brunt of the system, with high winds and intense rain causing widespread damage.

Holiday town Exmouth, 1250km north of Perth, copped the full force of Narelle's fury when the category four storm generated winds in excess of 250km/h.

Roofs were torn off buildings, power was lost, homes were flooded and some evacuees were forced to abandon the town's evacuation centre when it sustained damage.

Narelle tracked south to Coral Bay and made landfall just south of the town before weakening to a category three system.

It then passed east of Carnarvon on Friday afternoon, continuing to lose strength as it moved inland.

Thousands remain without power across Exmouth and Carnarvon, with fallen trees and debris posing ongoing risks as conditions remain unstable.

"There's been some extensive power outages across Exmouth and Carnarvon in particular," Emergency Management Minister Kristy McBain told ABC on Saturday morning.

"We do know the system is weakening, but there is still significant wind gusts and heavy rain that it is bringing."

The system is expected to continue moving southeast before likely exiting the south coast later on Saturday, with conditions expected to ease into Sunday, the bureau said.