The storm is forecast to cause destructive winds gusts of up to 230km/h, over 200mm of rainfall and a risk of flash flooding.
Severe Tropical Cyclone Narelle has intensified again into a category 4 storm as it barrels towards 800km of Western Australia's coastline.
The storm, currently sitting about 210km north-west of Karratha, is forecast to cause destructive winds gusts of up to 230km/h, over 200mm of rainfall and a risk of flash flooding.
It is expected to impact the west Pilbara and Gascoyne coasts today.
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A warning zone encompasses residents from Port Hedland to Denham, including Karratha, Onslow, Exmouth, Coral Bay and Carnarvon, and extending inland to Pannawonica and Gascoyne Junction.
Those south of Denham to Jurien Bay, including Kalbarri and Geraldton, and extending inland to Murchison, Yalgoo and Dalwallinu, are within the watch zone.
"Even though the system is offshore, it is quite a large system, so we're seeing some of those very strong wind gusts impact on shore," the Bureau of Meteorology's Ilana Cherny said in an update.
A flood watch has been issued for the western parts of the Pilbara, Gascoyne, Central and Lower West Coastal catchments.
The storm was a category 3 cyclone earlier this afternoon, but has been upgraded to a category 4.
WA Premier Roger Cook has asked locals to "heed the advice of emergency services".
"We know you've got experience in dealing with cyclone events but they are unpredictable," he said.
Narelle has travelled across northern Queensland, the Northern Territory and now to Western Australia over the past week, intensifying and easing and intensifying again.
The cyclone is currently moving down the coast at a slow 17km/h and is forecast to strengthen even further to a category 5 storm, according to the Bureau of Meteorology.
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Forecasting shows Narelle passing close to the North West Cape tomorrow before weakening as it turns inland across the South West Land Division on Saturday.
Narelle is expected to make a coastal crossing near Denham tomorrow night.
"The system will curve around the Exmouth coast as a category four system, before hugging the Gascoigne coast and eventually crossing the coast and continuing south eastwards as it tracks inland, eventually weakening it to a tropical low," Cherny said.
"That raises the question exactly when and where the system will move onshore.
"We are looking at a coastal crossing sometime on Friday evening or Friday night, and it looks most likely about the Gascoyne coast, so somewhere between Coral Bay and Kalbarri, with the Denham area looking like the most likely scenario."
Perth is in for a soaking, with up to 100mm of rainfall on the cards this weekend.
Some roads and ports across the state have been closed due to the storm.
Several events in Perth have also been cancelled, postponed or relocated in anticipation of Narelle's impact later this week, including the End of Summer concert and the Classic Car Show.
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Preparations get under way
Kalbarri, which is in the watch zone, knows how devastating a cyclone can be after being smashed by Cyclone Seroja almost five years ago.
Taking no chances this time around, locals were stocking up on sandbags and tidying up yesterday.
Caravan parks in Kalbarri, as well as those further north in Denham and Exmouth, are evacuating travellers and turning away any new bookings.
Locals Mark and Janice Murrie lived through the category 3 cyclone in 2021 and are worried about what is to come.
"There will be a lot of stressed people here," Mr Murrie told 9News.
"Because the mental health after the last one - people were just shell-shocked"
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