Flights have resumed arriving and departing from Adelaide Airport after delays and diversions this morning because of heavy fog.
Residual delays are expected as schedules get back to normal.
Fog blanketed Adelaide's western and northern suburbs from about 7:00am, causing international and domestic flights to be diverted from Adelaide Airport.
The airport confirmed two international flights from Singapore and Kuala Lumpur were diverted to Melbourne, along with two domestic flights, while other planes sat in a holding pattern over the city.
Flights from Broken Hill and Port Lincoln were also cancelled.
Adelaide Airport executive general manager Brenton Cox said the two international flights were still on the ground in Melbourne at 11:00am.
"Because while the fog's lifted from here, it's out to ocean, so traffic control are just giving them the heads up there is a chance it could roll back in later," he said.
Flights resumed landing and taking off from about 9:00am.
Civil Aviation Safety Authority spokesman Peter Gibson said planes had equipment to be able to fly in a variety of weather conditions but fog was a challenge.
"At some point you've got to be able to see the end of the runway if the fog's right down to the ground," Mr Gibson said.
The Bureau of Meteorology issued a road weather alert with fog affecting South Road, Salisbury Highway and Port Wakefield Road.
"Reduced visibility in areas of fog will make road conditions dangerous during Tuesday morning," it said.
It said it was the foggiest day at the airport since 2003.
SA Police have advised people to slow down, take extra care, leave more room between vehicles and turn on their headlights.
