Heavy winds and rain will ravage those areas.
"Widespread damaging winds through the west but it's the gust of about 130km/h that's going to cause damage to property," Sharpe reported.
Western Australia's Department of Fire and Emergency Services (DFES) acting assistant commissioner Jon Broomhall said it would be a "once-in-a-decade" storm.
"This is going to … test people's buildings, sheds, and all those unsecured items," he told the ABC.
"We're asking people to secure property, make sure everything loose is tied down.
"Normally our storms come from the south west and this will come from the north west.
Electricity companies are also bracing for significant outages and disruption to the grid as the cyclone wreaks havoc.
The state's capital won't be spared, with a cold front reaching Perth about 6am this morning.
"We'll see a new burst of wind and rain (for Perth)," Sharpe confirmed.
The extreme weather outlook appears to be a two-pronged attack by Mother Nature, by both air and sea, with the ocean also posing a significant risk.
Waves along the coast are expected to reach up to 8 metres high and will reach around 1,000km of coastline as it travels south from Sunday morning until Monday.
"Abnormally high tides (will) lead to coastal inundation," Sharpe said.
"We'll see very big waves coming into the west coast, particularly the central west and into the lower west in the Margaret River area.
"It'll by way too dangerous for anybody to be out in the water."
Emergency service also warned people not head out on the water.
"We don't need our marine rescue volunteers' lives put at risk by people making silly decisions to go boating or surfing in these conditions," Broomhall said.
However, conditions are meant to ease tomorrow.
"We'll then slowly see easing of conditions through Monday," Sharpe said.
