The weather bureau says strong winds and heavy rainfall are set to continue in Perth and the South West until Friday.
The warning comes as a wind gust of more than 100 kilometres per hour was recorded at Rottnest Island.
Heavy swells of up to seven metres and wind gusts exceeding 100 kilometres per hour will affect areas south of Bunbury tomorrow.
Perth can also expect long periods of rainfall with strong winds strengthening late tonight into tomorrow.
There have been a number of power lines that have come down across the city, including in Armadale, Willetton, Balcatta, Scarborough, Redcliffe and Byford.
There have also been two suburbs affected by falling power lines in Geraldton.
And, a power pole came down in Vivaldi Drive in Mandurah with its lines strewn across the footpath.
More than 50 millimetres of rain has fallen in Perth in the past 24 hours.
The Bureau of Meteorology's Neil Bennett says it is going to be a windy and very wet couple of days.
"It's looking as if rainfall is going to be probably in the order of 20 to 30 millimetres again," he said.
"Many places I think will get close to their May average by the end of this week and certainly by the end of the weekend."
Meanwhile, emergency services have responded to a number of traffic crashes across the metropolitan area.
A man believed to be in his 60s has been taken to Fremantle Hospital after his car rolled in Leeming.
Police are reminding motorists to adjust to the wet conditions and leave a greater braking distance between vehicles.
© ABC 2013
16:50 EDT An Indigenous development organisation has raised concerns about large payments being made to victims of Cyclone Lam.