Firefighters fear unfavourable conditions will cause a blaze burning south of Perth to break containment lines.
The threat from the fire burning near Baldivis was downgraded from an emergency warning to a watch and act early this morning.
About 180 firefighters are battling the blaze, which was has since burnt through more than 1200 hectares amid 50km/h winds.
The watch and act warning is in place for or people in an area bounded by Mortimer Road and Gossage Road to the north, Kwinana Freeway to the west, Karnup Road to the south, and Kargotich Road to the east, but not including the Kwinana Freeway.
The Department of Fire and Emergency Services said the bushfire was out of control and unpredictable and a threat to lives and homes remained.
“If you are not prepared or you plan to leave, leave now if the way is clear,” DFES said.
A bushfire advice is in place for people in an area bounded by Kwinana Freeway to the west, Thomas Road to the north, Kargotich Road to the east and Mortimer Road to the south, but not including the freeway, and an area bounded by Kwinana Freeway to the east, Karnup Road to the south, Baldivis Road and Johnson Road to the west and Mortimer Road to the north, but not including the freeway.
A number of roads have been closed including Folly Road and St Albans Road from Kwinana Freeway to Mundijong Road, Mundijong Road from Kwinana Freeway to Kargotich Road, Duckpond Road from Mundijong Road to Banksia Road, Young Road, Doghill Road and Horsfall Road.
There were unconfirmed reports the fire, which started at about 1pm was caused by a wheel coming off a boat trailer.
An evacuation centre has opened at Mike Barnett Sports Complex in Rockingham.
The Red Cross says people affected should register now to let family and friends know they are okay.
Fight to save homes
Yesterday several homeowners rushed to defend their properties but were stuck at road blocks, before some were let through.
Cattle farmer Andrew Newman said he feared for the livestock on his 44ha 110-acre property.
Mr Newman said while there was no houses on the property, he had sheds and several pieces of heavy machinery that were in the affected area.
With fire breaks, equipment and a 2000 litre tank at his place, Mr Newman said he was frustrated when an officer at a road block stopped him.
Within half an hour, he and others were escorted down Karnup Road.
One woman who was among those escorted through a road block was a part-owner of a racehorse business that reportedly had multimillion-dollar thoroughbreds, equine equipment and infrastructure in the area.