Authorities are warning of wild storm conditions set to smash the WA coastline in the coming hours.

Residents in homes across the Perth metro area, the South West and the lower South West have been told to “act now” to stay safe ahead of the severe weather.

The Bureau of Meteorology early on Wednesday alerted the public to a cold front bringing persistent rain and thunderstorms that will impact coastal areas and parts of the hills.

Heavy rainfall could cause flash flooding in parts of the South West and Lower West areas, the BoM said.

Between 30mm and 60mm of rain is expected across a six-hour period, with localised falls up to 90mm possible.

The heaviest falls are expected to fall from Mandurah down to Bunbury.

Rain is expected to shift north into Perth, before eventually pushing inland into the Wheatbelt and Great Southern throughout the day.

Rainfall is expected to ease in the early evening.

DFES has warned the public, particularly locals in the Bunbury, Busselton, Mandurah, Collie, Harvey and Dwellingup areas, to “act now and stay safe”.

The warning comes after 52.8mm of rainfall was recorded east of Busselton in the two hours before 9.30pm on Tuesday and 50.8mm was recorded at Ravenscliffe in the five hours to 12.30am on Wednesday.

The Department of Fire and Emergency Services has urged WA locals in the warning zone to:

• Pack away, secure or tie down outdoor furniture, trampolines and other loose items around your home that could be picked up and thrown by strong winds.
• Prepare an emergency kit with a radio that runs off batteries, a torch, spare batteries and a first aid kit.
• Review your plan and make sure everyone in your household knows what to do. If you do not have a plan, make one now on Emergency WA or in the Emergency WA app.
• Trim branches around your home to prevent them falling on your roof or car.
• Clear gutters and downpipes so they do not overflow after heavy rain.
• Boat owners should securely moor their boats.