A thick blanket of fog is creating dangerous conditions for Sydney commuters, with ferry services cancelled and drivers told to slow down.
The heavy mist reduced visibility early on Friday, prompting the Bureau of Meteorology to issue a road weather alert.
"Reduced visibility in fog will make road conditions dangerous during Friday morning," the bureau said.
"Motorists are advised to take extreme care."
All ferry services were cancelled on Friday morning due to poor visibility, and passengers were told to either delay trips or catch another form of transport.
Some services east of the Sydney Harbour Bridge resumed just after 7am.
Ferries operating west of the bridge did not resume until later, and all services were restored about 8.30am, the NSW Transport Management Centre said.