The fog which disrupted flights in Auckland and Hamilton on Thursday took until late afternoon to clear, but Auckland Airport staff are worried it may be back overnight.

Fog came in late on Wednesday in Auckland and stubbornly stuck around through until Thursday afternoon, inconveniencing hundreds of travellers.

There were 72 departing domestic flights cancelled and 22 delayed or rescheduled from Auckland Airport, with 71 arrivals cancelled and 31 delayed or rescheduled.

In addition, 11 international flights were delayed or rescheduled, four diverted to Wellington and two diverted to Christchurch.

"They were mostly regional flights, as the international flights and the larger domestic flights have the better technology to communicate with the ground," Auckland Airport spokesman Richard Llewellyn told NZ Newswire.

"It's been pretty disruptive and we feel for the passengers."

Mr Llewellyn said the airport was fully operational again by 4.37pm, but it may not be totally over.

"The forecast for tomorrow says there's a chance of fog."

Earlier in the day a flight from Rarotonga was diverted to land in Wellington.

The fog extended south to Hamilton airport, where a number of flight arrivals from Brisbane were cancelled.