Western Australia's Pilbara coast is being pummelled by gale-force winds and torrential rain from Cyclone Veronica, with authorities warning the system poses the biggest risk to the region in a decade.

Key points: Cyclone Veronica has started crossing the Pilbara coast, but the eye may not reach land

Cyclone Veronica has started crossing the Pilbara coast, but the eye may not reach land The system's size, combined with its slow movement, means its full force could be felt for 24 hours

The system's size, combined with its slow movement, means its full force could be felt for 24 hours BOM said Veronica poses the highest risk the region has seen from a cyclone in a decade

More than 179 millimetres of rain has fallen in Port Hedland in the past 24 hours, with much of it coming down sideways as powerful winds tear through the town.

Bureau of Meteorology (BOM) senior forecaster Steph Bond said residents could expect significant falls to continue.

"We do expect heavy rainfall over the next 24 to 36 hours … we could see figures up around 200 to 400mm and even isolated 500mm totals," she said.

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Veronica begins slow journey across the coast

The cyclone's core reached land about midway between Karratha and Port Hedland, while its centre was forecast to remain near the coast on Sunday night, according to the Department of Fire and Emergency Services (DFES).

James Ashley, BOM acting state manager, said the cyclone is significant because it is slow-moving.

"It's located roughly halfway between Port Hedland and Karratha, just off to the north of Wickham, about 40 kilometres off the coast," he said.

"It's very slow moving, drifting very slowly southwards. Being a Cat 3 system it's packing winds of up to 220 kilometres per hour in the core of the cyclone, which is currently impacting the coast midway between Port Hedland and Karratha.

Trees in Karratha and towns across the Pilbara are being blown over by the strong winds. ( Supplied: Ryan )

"The significant nature of this system is that it's slow moving, it's affecting a broad area all the way from Dampier to Port Hedland with gale force winds.

"Being slow moving means those damaging and destructive winds near the core of the cyclone will be impacting communities between Karratha and Port Hedland for much longer than would be expected for a cyclone.

"Heavy rainfall will be an issue and lead to flooding through that area. We've had falls of over 200mm or more through that area so far, and we expect that to continue throughout today [Sunday].

"We expect the very destructive core to be impacting the coast until late tonight, before the system starts weakening overnight … and during Monday."

The BOM advised that the destructive core would impact the coast until late Sunday night. ( Supplied: BOM )

He said the centre of the cyclone is off the coast and may never reach land.

"The main thing here is that the core of intense winds and heavy rainfall is right on the coast at the moment. We've seen wind gusts of up to 154 kph just observed at Roebourne," he said.

"That Roebourne, Wickham, Point Samson, Cossack area is experiencing very destructive winds at the moment and you would expect those conditions to be felt all the way along the coast between Karratha and Port Hedland.

"So despite the fact the cyclone centre is still off the coast, the conditions are as bad as they're going to get now right through the rest of today [Sunday].

"Rainfall will continue to be heavy right through the remainder of today in to [Monday]. As the cyclone weakens the rainfall will weaken as well and we're likely to see that start happening overnight tonight and tomorrow morning, and then by tomorrow afternoon it's likely the cyclone will be below cyclone intensity."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 11 seconds 11 s Cyclone Veronica rolls into Karratha

The BOM has warned that the system poses the highest risk the region has seen from a cyclone in the past decade, particularly with a sustained dangerous storm surge.

Mr Ashley said the storm surge risk to Port Hedland was reduced due to where the cyclone crossed the coast, but storm surges could still be significant along the Pilbara coast.

Darren Klemm, commissioner of the Fire and Emergency Services, said the safest place for residents was indoors.

"What I'd like to say to the people in the red alert area is the safest place for you right now is indoors, we must be clear this system will be prolonged and intense," he said.

Strong winds from Cyclone Veronica are also hitting Dampier. ( Supplied: Scooter )

"It's likely you will need to stay indoors for longer than you normally would. We know this might not be easy, but we do know it will be safer.

"Our emergency crews are working in a very challenging environment right now to make sure you stay safe, please help them to help you by staying indoors."

'Be patient, sit tight': Premier

Premier Mark McGowan received a briefing on the cyclone and said it was a very slow-moving and large cyclone that should not be underestimated.

"If you live anywhere between and including Karratha and Port Hedland, you need to be very careful and listen to all the advice that is being provided," he said.

"This will go on for some time yet, it's not one of those storms that will pass quickly, therefore, be patient and sit tight."

BOM said Cyclone Veronica was unusual because it was a very slow-moving system. ( RAMMB/CIRA )

Mr McGowan said people who had gone outside to take selfies in the storm were stupid.

"They're risking their lives and they're risking the lives of those people who are out there trying to rescue them," he said.

"So all I'd say to those people is you might think you've seen this before but all the advice is this is a massive cyclone and a big threat to life — so therefore listen to the advice and stay inside."

Emergency Services Minister Fran Logan thanked all of the emergency workers, police and local shires for the work they had been doing to prepare.

"It's moving between 8 and 10 kilometres an hour which means that the destructive winds and severe rain will be in the area for a long period of time, up to 12 hours," Mr Logan said.

"The red alert for the area is in place for a good reason — these are damaging, destructive winds and with the rain as well it presents a very, very dangerous situation for people."

Premier Mark McGowan was briefed by the Bureau of Meteorology. ( ABC News: David Weber )

'It's pretty hectic' in the Pilbara

Mitch, who lives in Wickham, said his street was littered with trees and debris from houses.

"Some trees have snapped halfway off and gone down onto someone's roof," he said.

"Another person's patio has broken off and fallen on to their car. Tin has been ripped off people's patios."

Lizzy Thompson's carport collapsed on her car during the strong winds. ( Supplied: Lizzy Thompson )

Wickham resident Lizzy Thompson also had her carport collapse on her car during a strong gust of wind.

"It's pretty hectic. I mean it started pretty early last night," she said.

"I lost my tree in the backyard and then this morning I heard a bit of a crash-bang and I lost my carport as well.

"It's sort of sitting on top of my car."

Point Samson, which is about 10 kilometres from Wickham, has lost power and has been cut off by road.

Ms Thompson said she has a friend who lives there.

"She's lost power. It's pretty hectic … [they are] cut off as well. They can't even come in if they need to," she said.

Winds are strengthening in Port Hedland. ( ABC News: James Carmody )

A red alert was issued on Saturday afternoon and is current for people in or near communities between De Grey and Mardie, including Port Hedland, South Hedland, Whim Creek, Point Samson, Wickham, Roebourne, Karratha and Dampier, but excluding Marble Bar.

People are being urged to stay indoors and stay away from doors and windows.

A blue alert is current for people in parts of the inland Pilbara, including Pannawonica.

An all clear advice is current for people in communities between Wallal to De Grey and inland to Marble Bar following the forecast that the cyclone is no longer expected to impact the Wallal to De Grey area.

Evacuation centres are operating at the JD Hardie Centre in South Hedland and the Karratha Leisureplex in Karratha.

In recent days volunteers have been helping to deliver enough food and water supplies to last several days.

The Karratha State Emergency Service offered a shuttle service to the evacuation centre for people who did not feel safe to drive last night.

A red alert was issued on Saturday afternoon and is likely to remain in place for some hours. ( ABC News: James Carmody )

New technology is being used to measure the impact of Cyclone Veronica on wave conditions and the coastline.

University of Western Australia (UWA) researchers have deployed a buoy to collect data on wave height, direction and duration during the cyclone.

UWA Researcher Dr Michael Culter said the technology would help assess cyclones in the future.

"The measurements we're taking are some of the first in Exmouth Gulf so they'll be quite critical for future predictions of what cyclones may do in the region," he said.

Concerns over premature alert

Some Pilbara residents have raised concerns about the premature issuing of a red alert by the BOM on Saturday.

BOM raised the alert from yellow to red about 6:00pm Saturday evening, despite DFES not intending to raise the warning level until 9:00pm that night.

Marshall Smith, pastor of the Roebourne Aboriginal Church, told ABC radio's AM program it was concerning.

Marshall Smith said it was concerning that a red alert was accidentally issued early. ( ABC News: Kendall O'Connor )

"For example … we picked up that from Wallal to Whim Creek was red, but then my daughter picked up that a little bit later on there was just a few minutes of red alert [for Roebourne] announced on the media," he said.

"Which created some question marks about, well, what are we hearing?"

"It is of concern for the public.

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"If the public are hearing different sorts of information on, especially this kind of emergency … [it] could sort of affect them thinking about how they could be able to move around and all that sort of stuff.

"I just hope that doesn't happen too often because … it does confuse the public who are sitting out there depending on good accurate information.

"We've got to be aware that everybody is constantly on either laptop or phones, just always constantly searching to see what information is around."

BOM's acting manager of weather services in Perth, Steve Duggan, said BOM provides DFES with scientific information for their emergency warnings. DFES then decides on the level of community alert, and BOM includes that alert in their own weather updates.

"Unfortunately yesterday, what happened was DFES provided those alerts and included an alert for an upcoming issue … and that future alert went into the current issue," Mr Duggan said.

"We were immediately made aware of the mistake … and we worked as quickly as we could to issue an update to that, I think it went out sort of 25 minutes later.

"We acknowledge the impact that going to a red alert early can have on the community, we're well-aware of what the conditions mean in a red alert, so it was an oversight of ours and we tried to rectify it as quickly as possible.

"But we do acknowledge the impact and are sorry to those who were potentially inconvenienced by it."

Babies born during red alert

A pregnant woman in her mid-20s was transported by ambulance during the red alert to Hedland Health Campus about 5:00pm Saturday.

The woman gave birth to a baby girl a short time later.

St John South Hedland paramedic Phil Stanaitis attended the scene, and said exceptions were made about going out during red alerts.

He said he had helped deliver babies during every cyclone he had been through in the Pilbara region over the last seven years.

Three other babies were delivered at the hospital in South Hedland on Saturday, while another was born in Karratha.

The following roads are closed and will not reopen until damage and flooding assessments have been carried out:

North-West Coastal Highway in both directions from Dewitt Road to the Great Northern Highway intersection

North-West Coastal Highway in both directions from Dewitt Road to the Great Northern Highway intersection Great Northern Highway in both directions between Auski Roadhouse and Sandfire Roadhouse

Great Northern Highway in both directions between Auski Roadhouse and Sandfire Roadhouse Nanutarra Munjina Road in both directions between Auski Roadhouse and Birngan Road

Nanutarra Munjina Road in both directions between Auski Roadhouse and Birngan Road Marble Bar Road in both directions between Great Northern Highway and Limestone Marble Bar Road

Marble Bar Road in both directions between Great Northern Highway and Limestone Marble Bar Road Karratha Tom Price Road (Warlu Road) in both directions

Karratha Tom Price Road (Warlu Road) in both directions Point Samson Roebourne Road in both directions

Point Samson Roebourne Road in both directions Dampier Road in both directions

Dampier Road in both directions Madigan Road

Madigan Road Ripon Hills Road in both directions