Tropical Cyclone Zelia is crossing Western Australia's Pilbara coast east of Port Hedland as a category five system amid fears of "catastrophic damage".
However, authorities confirmed the major mining hub of Port Hedland was likely to be spared the worst of the cyclone's impact.
Zelia was initially set to hit the region late on Friday with shops, schools, roads and ports in WA's northwest closed in preparation and locals warned to take shelter.
But authorities confirmed Zelia had crossed hours earlier than predicted, bringing damaging winds, flooding and heavy rainfall.
"We've got a whole raft of resources ready to go should they be required ... for really catastrophic damage," WA Fire and Emergency Services Commissioner Darren Klemm said.
WA Premier Roger Cook earlier confirmed the Australian Defence Force was on standby to assist, with Zelia triggering destructive wind gusts of up to 290km/h, intense rainfall and flash flooding.
Port Hedland, which had been fearing the worst after the category five Cyclone Ilsa system struck in 2023, claiming eight lives, was expected to dodge a bullet.
"Port Hedland is not expected to be impacted by the very destructive winds," the Bureau of Meteorology's Matt Collopy said.
Port Hedland Deputy Mayor Ash Christensen said there had been an "eerie sort of feeling" around the community as residents waited for the cyclone to strike.
"We put a brave face on but I think everyone, deep down inside are a little bit worried about this one," he told AAP.
Zelia rapidly intensified as it zeroed in on Australia's coast, developing from a category three to a five in 24 hours - progress experts claimed was "highly unusual".
Evacuation centres have been set up at Karratha and South Hedland, with major highways near Port Hedland and regional airports closed.
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