Explained: What caused Auckland's once-in-a-generation drought

Auckland's once-in-a-generation drought had its beginnings halfway across the world about seven months ago, a meteorologist says.

"This actually had its beginnings some 8000 kilometres away from New Zealand in the Indian Ocean in late 2019. Something called the Indian Ocean dipole was in its strongly positive phase," NIWA meteorologist Ben Noll told Newshub.

"And that means that ocean temperatures to the north of Australia, near Indonesia, were cooler than average. That's an important region as those systems pull down moisture from the north as they track toward New Zealand.

"But because those seas in the Indian Ocean were cooler than normal they weren't able to extract as much moisture as they normally would be, as they approached New Zealand from the west.

"So for us, that is really what kickstarted, or ignited, the lack of rainfall."

Watch the full interview above for a detailed description of the meteorological reasons behind Auckland's drought.