Australian cyclone crossing Western Australian coast

Severe tropical cyclone Rusty had been sitting offshore for several days, slowly intensifying as it edged towards the Pilbara coast and bringing heavy rain and gale-force winds to the iron ore region.

"It is in the process of crossing," Neil Bennett from Australia's Bureau of Meteorology told AFP just after 0700 GMT, adding it was too soon to say whether it had caused any damage.

"Wind gusts in excess of 165 kilometre an hour are in that area."

Bennett said the storm had been downgraded from a category 4 storm, just one notch short of the top category, to a category 3.

The bureau had expected Rusty to make landfall close to Port Hedland, 1,300 kilometres (800 miles) north of Perth, but Bennett said the major iron ore port appeared to have escaped the full brunt of the storm.

"It looks as if Hedland has dodged the bullet, so to speak, because the worst of the winds are away from Hedland," he said.

 "Hedland though has been experiencing a constant period of gale-force winds for over 36 hours now. And that's unprecedented (for that area)."

While the storm has been downgraded, its eye has also contracted from being about 80 kilometres wide on Tuesday to about 50 kilometres by the time it crossed land.

Authorities had warned residents to move out of the storm's path or seek shelter. Resident Ian Badger said he was seeking refuge at the Pardoo Roadhouse, about 120 kilometres from Port Hedland.

"It's just a matter of hanging on," he told the Australian Broadcasting Corporation.

"The amount of water that's around is a bit worrying. The ground is very sodden, very soft. As soon as you get a get a bit of strong wind, trees start going over."

The weather bureau expects the cyclone to move slowly in a south-southeasterly direction, gradually downgrading to a category 1 storm by Thursday afternoon and a tropical low the following day.

Australia's major iron ore export ports have been shut for several days anticipating Rusty's approach. Hundreds of people have been forced to evacuate their homes in the sparsely populated but cyclone-prone area.

Global iron ore giants including BHP Billiton, Rio Tinto and Fortescue Metals Group have all shut down or scaled back operations due to the storm.