Tropical Cyclone Zelia has rapidly intensified since developing off the Western Australian coast.

About a dozen schools have been shut in WA's north, and roads are set to be closed as the cyclone looms about 140km north of Port Hedland.

Cyclone Zelia is currently a severe category four system that is moving slowly southwest toward the Pilbara coast and intensifying.

It is set to develop into a maximum category five system and cross the coast west of Port Hedland on Friday night.

Schools have been closed in the region, and authorities are expected to close roads, including the Great Northern Highway, and set up a South Hedland evacuation centre.

The current category four system is developing wind gusts up to 250m/h.

A cyclone watch and act warning has been issued for Eighty Mile Beach to Whim Creek and inland to Marble Bar.

"There is a possible threat to lives and homes as a cyclone is approaching the area," the warning said. "You need to take action and get ready to shelter from a cyclone."

Australia's largest iron ore port at Port Hedland was shut down on Wednesday as the region braced for the incoming system.

With AAP.