Heavy fog envelops Sydney, delaying flights and slowing motorists

Heavy fog enveloping Sydney is threatening to slow morning commutes and delay flights out of the airport.

Drivers have been warned to take extra care navigating the thick mist settling over major roads.

The low-lying fog is also affecting traffic in low-lying areas of the M1, with motorists advised to expect delays.

Virgin Australia has advised that some smaller flights departing out of Sydney will be delayed as air traffic controllers wait for the mist to lift.

Meteorology service Weatherzone advises that rising sun should burn off the fog from almost all of Sydney by 9am.