Western Australians are being urged to brace for wild weather tomorrow with preparations in the Pilbara as a cyclone forms off the coast.

A tropical low is expected to intensify into Tropical Cyclone Sean and track along the Pilbara coastline but it is not expected to make landfall.

The Bureau of Meteorology said damaging wind gusts and heavy rain may hit Port Hedland, Karratha and Dampier from tomorrow morning.

The system is expected to then move south to Exmouth.

The Port of Port Hedland has been closed with all boats to leave tonight.

“With those very strong gale force winds and a bit of swell around, it’s going to be very rough seas,” forecaster Luke Huntington said.

Meanwhile the south-west is preparing for extreme heatwave conditions.

Temperatures are forecast to climb as high as 42 degrees next week.