Main Roads has issued the warning along with advice for motorists this morning.
The fog is expected to be worst between Thomas Road and Mortimer Road in both directions.
Motorists are urged to turn on headlights and keep a safe breaking distance between other cars.
Extra travel time should also be taking into account due to reduced visibility.
Mandurah Crab Fest boasts huge range of free, family friendly entertainment
The Channel 7 Mandurah Crab Fest is set to dish up a huge range of free, family friendly entertainment and activities this weekend (March 14 and 15).
Fuel prices surge in Perth, Mandurah
Fuel prices have surged to near record highs in Perth and Mandurah.
Teen boys charged over Mandurah burglaries
Two teenage boys have been charged following an investigation into a series of alleged burglaries in the Mandurah area.
Tragic update in search for missing man Robert Snyder
Police have confirmed they have located a body believed to be missing man Robert John Snyder.
Premier Roger Cook to leave Kwinana electorate, move to Perth
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Mandurah Marine Rescue's new vessel named in memory of nun who survived 1959 boating accident
Mandurah Marine Rescue have added a new vessel to their fleet, strengthening emergency response times across one of Western Australia's busiest waterways.
Teen dies in motorbike crash at Waroona Dam
A 14-year-old boy has died in a tragic motorcycle crash at Waroona Dam.
Shark alert issued after whale carcass reported at Preston Beach
A shark advice has been issued for Preston Beach, south of Mandurah.
Kwinana businesses to refuse serving students during school hours
Local businesses in the City of Kwinana are teaming up to keep kids in school.
