Fog restrictions were put in place at the airport about 6.30am on Wednesday.
Eleven regional flights were cancelled, and 19 delayed.
Five flights to and from Christchurch and one to Queenstown were facing delays.
No international flights have been affected.
Travellers were advised to check with their airline for the latest updates on their flight.
MetService meteorologist Oscar Shiviti said the fog should clear by midday and fine conditions were expected for the rest of the day.