UPDATE: The mist is finally starting to clear, though there are still flight delays at Sydney Airport, and disruptions to ferry services.
Ferry services that use Sydney Harbour including the Manly Ferry were all suspended early Saturday morning, but have now started to resume as the fog lifts.
Passengers are advised to delay their journey, use alternative public transport and allow additional travel time.
"There are still flights coming in, but obviously for safety reasons everything is slowed down," a spokeswoman from Air Services Australia said.
The Bureau of Meteorology expects northwesterly winds of 15 to 20 km/h in the early afternoon and sunny conditions.
CHECK OUT THE GALLERY OF FOG: