A severe weather warning has been issued for Western Australia's south-west, with damaging winds and heavy rain forecast to hit Perth and regional areas.

Key points: Winds could reach 100 kph and heavy rain could cause flash flooding, the BOM says

Winds could reach 100 kph and heavy rain could cause flash flooding, the BOM says Perth is set to cop up to 30mm of rain on Saturday and up to 10mm on Sunday

Perth is set to cop up to 30mm of rain on Saturday and up to 10mm on Sunday The latest cold front is expected to see the city far exceed its June rainfall average

The Bureau of Meteorology (BOM) said a strong cold front would move across the area on Saturday afternoon, bringing wind gusts of up to 100 kilometres per hour along with heavy rain, thunderstorms and possible flash flooding.

Areas to be affected include Perth, Albany, Bunbury, Busselton, Katanning, Mandurah, Manjimup, Margaret River, Merredin, Moora, Mount Barker, Narrogin and Northam.

Heavy rainfall could lead to flash flooding across the warning area, the BOM says. ( Supplied: BOM )

"The potential for damaging winds commences from around 3:00pm Saturday in coastal parts between Jurien Bay and the South West Capes, including the Perth metropolitan area," the Department of Fire and Emergency Services (DFES) said.

"This area will extend eastwards to include Narrogin, Katanning and Albany by 8:00pm and to Hyden and Hopetoun by around midnight Saturday.

"Heavy rainfall that may lead to flash flooding is possible over the warning area."

Perth is expected to receive up to 30 millimetres of rain on Saturday and up to another 10mm on Sunday.

The latest severe weather comes after a series of storms hit the state a fortnight ago, delivering winds in excess of 100kph and driving rain, and whipping up dangerous surf along the coast.

The coastline bore the brunt of the storms, with erosion visible at several Perth metropolitan beaches.

The erosion even forced the City of Fremantle to dump tonnes of sand in front of buildings which were in danger of collapsing into the ocean at Port Beach.

The temporary move was designed to give immediate protection to the buildings as the Council considered building a sea wall.

An excavator shores up sand on Port Beach after erosion from a storm. ( ABC News: Nicolas Perpitch )

The early winter drenching has seen Perth record 119.2mm of rain since the start of the month, almost reaching its June average of 124.5mm.

This latest cold front is expected to see the city far exceed its average, while also delivering double-digit totals to inland areas.

The BOM is also forecasting more wild weather during the week, with Wednesday and Thursday both expected to see a possible storm and up to 25mm of rain.

Perth forecast

Saturday: Rain, possible storm. 15-30mm rainfall. 21C

Rain, possible storm. 15-30mm rainfall. 21C Sunday: Showers, possible afternoon storm. 4-10mm. 12–20C

Showers, possible afternoon storm. 4-10mm. 12–20C Monday: Partly cloudy. 11-20C

Partly cloudy. 11-20C Tuesday: Partly cloudy. 9-21C

Partly cloudy. 9-21C Wednesday: Showers, possible late storm. 8-20mm. 11-20C

Showers, possible late storm. 8-20mm. 11-20C Thursday: Showers, possible storm. 8-25mm. 10-17C

Showers, possible storm. 8-25mm. 10-17C Friday: Shower or two. 0-3mm. 5-16C

AAP/ABC