Nearly 50 flights have been disrupted and hundreds of passengers are stranded at Wellington Airport because of heavy fog.

Photo: RNZ / Kim Savage

MetService was warning the fog, which has led to the cancellation of at least 33 flights, may not clear until Monday afternoon.

Another eight flights have been delayed, while eight flights into Wellington have been diverted.

Many have spent the night queuing at airline counters at main centre airports to find out what to do next.

Photo: RNZ / Kim Savage

Photo: SUPPLIED

Some passengers have been re-booked for flights on Monday morning.

But Sarah and her partner were still waiting to find out whether they would make it home to Dunedin tonight.

"It's delayed from Auckland so we can't check in until it's actually landed so we don't know what way it's going to go at this point but if everything else has been cancelled, chances [that it will be cancelled] are high," she said.

Customers at Wellington Airport were given meal vouchers but had to wait in line so they could rebook their flights and sort accommodation for the night.

Dionne and her friend Tara first got to the airport for a flight to Melbourne at 4am this morning.

"We were at customs at 6 o'clock, and then 10 minute delays, 15 minutes, 15 minutes, and then told to come back ... to find that we need to go back home for like the third time."

The pair hoped to fly out to start their holiday on Monday morning but MetService forecaster William Nepe warned the fog may not clear until the afternoon.

He said the fog, which was at sea level, should move south.

"Given the current set up it's not really changing until tomorrow afternoon. It looks like this warm moist air starts to sink south and also we do expect some rain and when you get rain coming out of it, it does take the fog droplets out of the air."

William Nepe said the fog was a result of warm, moist air coming down from the tropics.

Travellers were asked to contact their airline for information.