Kalbarri has been decimated by ex-Tropical Cyclone Seroja with authorities estimating damage to about 70% of the town’s buildings.

Northampton also bore the brunt of the cyclone which left a trail of destruction in its wake when it slammed into WA"s mid-west coast last night.

Homes have been destroyed and more than 30,500 residents were left without power after the cyclone made landfall as a category three storm about 8pm, bringing wind gusts of up to 170 km per hour.

Phone services have also been affected, with Telstra reporting widespread outages to its mobile network.