A strong cold front may cause severe weather and flooding in parts of Western Australia during the next 24 hours.

A front moving across the Indian Ocean will reach the state's southwest capes this evening, before sweeping over the South West Land Division into Thursday morning and then crossing remaining southern parts of the state by Thursday night.

Showers, thunderstorms and blustery winds will accompany the front, with damaging gusts possible near the front as it passes over the state's southwestern districts.

While rain will not be unusually heavy for this time of year, will be falling in already saturated catchments following a recent spate of rain-bearing systems. A flood watch has been issued for the Central West, Lower West and South West districts, where rapid stream rises may lead to riverine flooding on Thursday.

The heaviest rain in Perth will be early on Thursday morning, although fresh onshore winds behind the front will maintain showers throughout the day.

In addition to the rain, a pool of cold air behind the front is likely to produce small hail in the state's southwest, mainly from Thursday afternoon.

Showers will contract to the state's south coast on Friday as the front moves into South Australia, before drier weather returns across the state on the weekend.

As of 9am on Wednesday, Perth had already collected 361mm of its average winter rainfall (394mm) so far this season. This is Perth's highest total to this point in the season since 2011 and the second highest in 18 years.