Heavy fog has stopped or delayed several domestic flights in and out of Auckland.
Auckland Airport said 12 regional flights have been cancelled and 11 domestic regional flights had been delayed because of fog restrictions.
"Due to earlier fog in Wellington and fog in Auckland, there are multiple delays to main trunk domestic flights, particularly Wellington and Christchurch,'' a statement said.
International flights are not affected.
Auckland motorists are also being urged to take extra care on the roads this morning, as thick fog restricts visibility.
The NZ Transport Agency alerted those driving into the city from West Auckland, on the Northwestern Motorway, that there is thick fog from Royal Rd through to St Lukes.
Fog is also affecting drivers on the other side of the city - southbound from the Waterview Tunnel through to Māngere Bridge.
A MetService spokesman told the Herald their cameras were showing shallow fog in and around the airport.
However, arrival and departure information on the Auckland Airport's website - both for international and domestic terminals - indicated no flights had been affected yet.
The MetService said a ridge of high pressure over the North Island over the past few days had brought clear skies and light winds; which resulted in foggy conditions.
This morning's fog is expected to lift by mid-morning, he said.
Although it was difficult to forecast fog, the spokesman said, it was likely foggy conditions would be seen throughout the rest of the week as well.
A number of readers have sent through photos of fog on the way to work this morning.
Earlier this week, flights in and out of Wellington were disrupted because of heavy fog in the city.
Among passengers to be affected were the All Blacks, whose flight from Auckland to Wellington had to be turned back as a result.