An out-of-control bushfire burning for days has blackened almost 12,000 hectares north of Perth, as warnings for residents to leave continue.
A "seabreeze" of up to 50km/h was expected to put extra pressure on the northeastern edge of the blaze on Saturday after an earlier westerly, Fire and Emergency Services Commissioner Darren Klemm told reporters.
"People in Guilderton and Woodridge should leave now ... towards Indian Ocean Drive and use Gingin Brook Road to travel towards Gingin as fire is approaching the area," an Emergency WA warning said.
"It is not safe to leave for people in Seatrees and Breakwater Estates."
The warning covers Guilderton, Two Rocks, Woodridge, Gabbadah, Wilbinga, Caraban, Seabird, Yeal, Redfield Park, Sovereign Hill, Seatrees, Breakwater Estates, parts of Beermullah, Muckenburra, Wanerie, Neergabby and Yanchep.
A watch and act alert is in place for other parts of Yanchep, parts of Eglington, Breton Bay, parts of Gabbadah and Wanerie, Seabird and parts of Ledge Point.
"By the end of today we will be in the vicinity of 12,000 hectares," Mr Klemm said, adding the changing wind directions had put pressure on all sides of the fire.
"We are also seeing light fuel areas ... where we would historically have some confidence to pull up the fire in those lower fuel areas but that hasn't occurred. The fire has gone through those areas really quickly.
"We have seen the fire extend during the night time when you don't have access to the aircraft. So it rolls up to really difficult circumstances."
Firefighters are working around the clock to contain the blaze despite containment lines being breached day and night.
"People need to be aware things could escalate from here in terms of the damage," Mr Klemm said.
The fire has already burnt more than 11,000 hectares of land and so far a home and service station have been destroyed in Yanchep.
"We are anxiously waiting to be able to see the remains of what once was the backbone of Yanchep," the Vaz family wrote on social media of losing their service station.
Some other outbuildings have also been damaged, the fire service says.
The temperature hit a top of 41C in Perth on Saturday, with Sunday set for 40C.
There won't be any reprieve until Monday when the temperature is set to drop to 33C.
Temporary evacuation centres have been set up at Gumblossom Community Centre in Quinns Rocks and Granville Civic Centre in Gingin.
Australian Associated Press