Lingering fog is preventing dozens of flights from getting in and out of the South Island’s main airports today.

“Fog is impacting visibility and has led to some disruptions in Christchurch and Dunedin this morning,” Air New Zealand chief operating officer Alex Marren told the Herald.

This morning a Christchurch Airport spokesperson said there were at least 20 delayed flights and a “small number” of cancellations resulting from the haze, with more expected over the course of the day.

“Unusually, it’s hanging around longer than normal,” the spokesperson said.

“The situation is compounded when aircraft which can’t land disrupts the outgoing schedule even more.”

Marren said safety was Air New Zealand’s priority and thanked customers for their patience while they dealt with the disruptions.

Fog has disrupted dozens of flights at Christchurch and Dunedin airports today. Photo / Sarah Ivey

Christchurch Airport acknowledged disruptions might be causing frustration among passengers but said the terminal remained open for those awaiting flights.

“Some aircraft have managed to land, including Singapore Airlines, and others have departed in small windows of opportunity.”

While flights in and out of Dunedin appeared to be returning to normal, persistent fog in Christchurch was continuing to disrupt the southern city’s flight schedule.

A Fiji Airways flight from Nadi and an Air New Zealand flight from Palmerston North had been diverted from Christchurch to Wellington in the past hour.

Meanwhile, at least five inbound flights scheduled to land between 1pm and 2pm have been cancelled.

These were travelling from Auckland (JQ231), Wellington (NZ5371), Invercargill (NZ5710), Rotorua (NZ5785) and Tauranga (NZ5803).

Marren urged travellers with flights booked today to monitor the Air NZ app for any delays or changes to the service.

As of midday, FlightRadar24’s disruption index for Christchurch Airport was at five – the highest it can be valued – meaning it’s facing “major problems with long delays and several cancelled flights”.

There is an average delay of 120 minutes for flights arriving and 51 minutes for those departing.

Dunedin Airport has been approached for comment.