Damaging wind gusts are possible around the escarpment during late Thursday evening and Friday morning.
A high pressure system to the south of the state and a trough deepening along the coast to the north is resulting in a strengthening easterly airstream over parts of southwestern Western Australia later this evening and on Friday morning.
Easterly winds with damaging wind gusts of around 90 km/h are possible in the warning area, this includes the Perth hills.
Wind gusts will begin to strengthen as early as as 11:00 pm AWST on Thursday evening and continue through until around 9:00 am AWST on Friday morning.
This weather is not typical for this time of the year and may cause damage to homes and properties.
Locations which may be affected include Dwellingup, Ellenbrook, Gingin, Harvey, Kalamunda and Midland.
The Department of Fire and Emergency Services advises that people should:
* If outside find safe shelter away from trees, power lines, storm water drains and streams.
* Close your curtains and blinds, and stay inside away from windows.
* Unplug electrical appliances and do not use land line telephones if there is lightning.
* If boating, swimming or surfing leave the water.
* Be alert and watch for hazards on the road such as fallen power lines and loose debris.
* Keep away from flooded drains, rivers, streams and waterways.
* Be careful of fallen trees, damaged buildings and debris.
* Be careful of fallen power lines. They are dangerous and should always be treated as live.
* Assess your home, car and property for damage.
* If damage has occurred take photos and contact your insurance company to organise permanent repairs.
* If your home or property has significant damage, like a badly damaged roof or flooding, call the SES on 132 500.