Dunedin Airport marketing and customer experience manager Chris Snow said fog resulted in several disruptions yesterday morning.
An inbound flight from Christchurch was cancelled and as a result, the corresponding outbound flight was unable to depart.
A flight from Auckland was also delayed by an hour.
Fog is a metrological condition which happens when cloud got down to the ground and impaired visibility.
It is typically seen at the coldest hours of the day, before lifting as temperatures rise.
The temperature around Dunedin had been about 16degC overnight but it was very humid, with warmer air coming from the north, Mr Hines said.
Because coastal Dunedin was relatively colder, the humid air cooled to a low temperature causing ‘‘advection fog", which was a type of fog caused by movement — typically warm air moving over cooler oceans.
Later in the afternoon, about 4000 lighting strikes were recorded across the South in the four hours from 11.30am.
A general thunderstorm watch was placed from South Canterbury to Southland, along with four specific warnings, which was unusual.
Riversdale and Duntroon were among the rural communities covered by the warnings.
The afternoon thunderstorms were not directly linked to the fog but were caused by similar atmospheric conditions.
Thunder formed in a different way, due to vertical movement in the atmosphere.
It was not unusual for them to happen in summer as they needed heat, Mr Hines said.
