Fog is causing disruption to Air New Zealand's regional turboprop and domestic jet services across much of the South Island and in and out of New Plymouth.
Multiple services have been cancelled or significantly delayed on Tuesday morning and the disruption is likely to impact the schedule for much of the day.
Domestic jet operations in and out of Christchurch and Dunedin have also been impacted.
Air NZ says disrupted customers are being offered road transportation options where viable.
"Those booked to travel on affected flights have the option to transfer their booking to another date by managing their booking online without the need to phone the airline’s contact centre," the airline said in a statement.
Customers are advised to keep an eye on the Air NZ arrivals and departures page for the most up to date flight information.
Some Jetstar flights have also been affected.