Australia Weather News

Water Police are urging people across Western Australia's southern half, including Perth, to avoid the sea or ocean amid "atrocious" conditions.

A storm was forecast to hit the South West and metropolitan area about 8:00pm Saturday night, bringing strong winds and rain.

Winds of up to 100 kilometres per hour along the Rockingham coast overnight already tore part of the roof off an apartment complex in Calista.

Emergency crews were called to Edmund Way about 1:00am as some sections of the roof landed on nearby power lines.

The complex lost power and residents were evacuated.

Water Police Acting Sergeant Marty Allen said conditions on the water, between Jurien Bay and Esperance, would be dangerous for several days.

"There are large seas, large swell, quite a bit of wind and we just don't want people going out there and getting in trouble," he said.

"That includes not only people going out on the boats but also people fishing from rocks, the shore, tourists going to local locations where there are cliffs."

Sgt Allen said the swell around Rottnest Island was currently about 5 metres and was likely to stay at that level for a few days.

"As the weather improves, the ocean may appear to be nice and calm but there's still a large swell running and that is when a lot of boats get into trouble because they think it's calm but there are large swells and they go to areas that they shouldn't," he said.

"You may have all the gear but sometimes things happen quickly out on the ocean and it's not always possible to get to that stuff."

Sgt Allen encouraged boaters to use this time instead to perform maintenance.

"Check your boat over, check your safety gear, make sure everything's working properly and get your motor serviced," he said.

Second storm to bring 'potentially gale force winds'

Bureau of Meteorology duty forecaster Austen Watkins said a storm was likely to hit the South West Capes region around 8:00pm on Saturday, and move to the metropolitan area by midnight.

"We'll see showers increasing through the Perth area around that midnight and early morning period, showers and gusty winds, potentially some small hail as well and also some isolated thunderstorms are also possible," he said.

Mr Watkins expected most of the showers would clear by about 3:00am or 4:00am.

He said there was a strong-wind warning for local waters from Lancelin, north of Perth, right around to the South Australian border.

"For Perth, westerly winds up to 30 knots, seas and swell upwards of 5 to 6 metres so there is a caution for dangerous surf conditions," he said.

"We're set to get very similar conditions on Monday with another fairly strong cold front moving through. It looks a little bit stronger, even potentially gale-force winds over the Perth waters."