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.
Early voting for Secret Harbour by-election begins Monday
Early polling for the Secret Harbour by-election will open on Monday, August 17.
Welfare concerns for missing Swedish national last seen in Warnbro
Rockingham Police are asking for the public's help to find a missing Swedish national who has not been seen in more than 10 days.
Wanted man last seen in Golden Bay
WA Police are looking for a 46-year-old man who may be able to assist them with an ongoing investigation.
Passenger critically injured in West Pinjarra crash
A passenger is fighting for life in hospital following a serious crash in West Pinjarra.
Unregistered painter fined for requesting hefty deposit from Singleton homeowner and not doing the job
A local tradie has been fined $4500 after being convicted of three building service offences.
Police hunt driver following dangerous Baldivis pursuit
Police are hunting an alleged reckless driver who got away from them in Baldivis last week.
Welfare concerns for boy last seen at Port Kennedy skate park
Rockingham Police hold welfare concerns for a missing 12-year-old boy.
Rubbish truck catches fire in Baldivis
A rubbish truck has caught fire in Baldivis.
Driver injured in bus crash in Rockingham
A driver has been rushed to hospital with serious injuries after a crash in Rockingham.