A severe weather warning has been issued for Mandurah, Perth and the South West.
Severe thunderstorms are expected to hit around 2pm on Sunday and continue for the rest of the day.
They are likely to produce damaging winds and heavy rain which could lead to flash flooding.
"Locations which may be affected include Bunbury, Busselton, Geraldton, Mandurah, Margaret River and Perth," a Bureau of Meteorology spokesperson said.

WHAT TO DO:
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If outside find safe shelter away from trees, powerlines, storm water drains and streams.
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Close your curtains and blinds, and stay inside away from windows.
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Unplug electrical appliances and avoid using landline telephones if there is lightning.
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If there is flooding, create your own sandbags by using pillow cases filled with sand and place them around doorways to protect your home.
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If boating, swimming or surfing leave the water.
IF DRIVING:
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Do not drive into water of unknown depth and current.
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Slow down, turn your lights on and keep a safe distance from other drivers.
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Be alert and watch for hazards on the road such as fallen powerlines and loose debris.
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If it is raining heavily and you cannot see, pull over and park with your hazard lights on until the rain clears.
IF YOU NEED ASSISTANCE:
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If it is safe to do so, please do what you can to help yourself before calling the SES for assistance.
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If your home has been badly damaged by a storm, call the SES on 132 500.
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In a life threatening situation call 000.
After a storm SES volunteers make temporary repairs to homes that have been badly damaged, such as roofs that have been ripped off or large fallen trees on homes or cars.
Please contact your insurance company to organise permanent repairs.
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