A storm advice warning has been downgraded for parts of Perth and southern WA, as two cold fronts moving across the State threaten to cause flash flooding.

A storm advice alert — issued by Emergency WA at 4.34pm on Monday afternoon — was issued for parts of the Perth metro area including Rockingham, Armadale, Fremantle, and Kalamunda.

The towns of Narrogin and Wagin are also included in the alert, which has since bene downgraded to a reduced threat.

Heavy rainfall is expected for those areas, with BoM warning it could lead to flash flooding.

“The immediate threat has reduced however you need to be aware of potential hazards that remain after the storm has passed,” an Emergency WA statement said.

Earlier, the Bureau of Meteorology issued a severe weather warning at 1.59pm on Monday, which has since been cancelled.

Perth is expected to cop up to 25mm of rain.

The warning comes just hours after 28.2mm of rain was recorded at Quaelup within just 30 minutes, and 25.2mm was recorded in Balingup over one hour.