MetService duty forecaster Tom Bell said the "radiation fog" had been caused by a humid air mass contrasting with cooler ground temperatures.
Radio New Zealand reported that some Auckland harbour ferry crossings had also been delayed.
A police spokesman said a few minor crashes had occurred around the Auckland region this morning but it wasn't possible to say whether they were the result of fog.
"We had a crash reported up on the Northern Motorway between Oteha Valley and Bawden Rd hearing north - a nose-to-tail. There's no report of injury at this stage. I can't say whether we can blame the fog on it or not," he said.
The NZ Transport Agency warned Auckland motorists to take extra care at East Tamaki Rd and Springs Rd intersection as a collision had taken out the traffic lights at the intersection. No one was injured in the crash and the car was being towed from the scene, the police spokesman said.
Motorists were advised to drive with caution.
Fog warning to drivers
Motorists are being advised to drive with caution as thick fog covers parts of Auckland.
Auckland Airport spokesman Simon Lambourne said fog restrictions were put in place at 4.38am this morning.
Three regional departures destined for Taupo, Wanganui and Whangarei from Auckland Airport have been delayed due to fog.
International flights were not affected, airport spokesman Simon Lambourne said.
Fog restrictions at the airport continued.
Passengers were advised to check the airport's website for the latest flight arrival and departure information.
MetService duty forecaster Tom Bell said he expected the fog to clear shortly.
"There's still some low cloud around but that seems to be generally clearing as well and I don't expect it to come back."
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The "radiation fog" had been caused by a humid air mass contrasting with cooler ground temperatures, Mr Bell said.
A Police Northern Communications spokesman said a few minor crashes had occurred around the Auckland region this morning, however it wasn't possible to say whether they were the result of fog or not.
"We had a crash reported up on the Northern Motorway between Oteha Valley and Bawden Rd hearing north - a nose-to-tail. There's no report of injury at this stage. I can't say whether we can blame the fog on it or not."
The NZ Transport Agency warned Auckland motorists to take extra care at East Tamaki Rd and Springs Rd intersection as a collision had taken out the traffic lights at the intersection. No one was injured in the crash and the car was being towed from the scene, the police spokesman said.
Motorists were advised to drive with caution.
