Sydney Airport Chaos As Fog Shrouds The City

Travellers have been left stranded at Sydney Airport as a thick blanket of fog enshrouded Sydney on Wednesday morning.

Dozens of departing domestic and international flights were delayed or cancelled, while some arriving flights were diverted away from Sydney.

Some flights have been delayed for two hours as the fog lingered well into the morning.

Sydney Airport domestic departures list. Image: Sydney Airport

Sydney Airport has told travellers to check with their airlines for their flight status.

Delays and cancellations in Sydney have had a flow on effect around the country, with Brisbane Airport also warning passengers about possible delays.

For those lucky enough to be on a flight above Sydney, they were treated to a spectacular view of a city in fog.

Image: Danny Lattouf

Images show how thick the the fog was, with just the tops of the tallest buildings visible as they poked through the veil, while the ANZAC Bridge all but disappeared from view.

Image: Danny Lattouf

Sydney ferries on the Harbour and on Parramatta River were also cancelled at about 9am, but resumed service about an hour later.

However, Transport NSW issued a warning for commuters to allow extra travel time as the services return to normal.

Morning commuters were told to take extra care while driving to work as the Bureau of Meterology issued a Road Weather Alert in all suburbs because of reduced visibility.

Some people reported they couldn't see more than 10 metres in front of them.

For fog to form, there needs to be clear skies and very light winds, allowing water vapour to condense as the temperature cools.

Conditions overnight were perfect for the fog to blanket Sydney, the Bureau of Meteorology told 10 daily.

"We had a fair bit of moisture left over from showers yesterday, and as the temperature cooled overnight the clear skies and calm wind meant fog could form," a spokesperson said.

"It was also helped by a high pressure system sitting above us."

Richmond, in the city's far west, started seeing fog form at about 2 am and continued to spread, reaching Sydney Airport at about 5.30 am.

The fog is expected to disperse by mid morning, as the temperature rises and the fog becomes low cloud.