New Zealand’s biggest city had its wettest month in January, with more than half a metre of rainfall in central Auckland - smashing a record from 1869.

There was a total of 539mm of rain at Albert Park, beating the previous monthly record of 420mm recorded in February 1869.

Honorary associate professor Anthony Fowler, from the School of Environment at the University of Auckland, said nothing in the observational record came close to what we’ve seen in the past few weeks.

“Total January rainfall was more than twice the previous record for the month, contributing to an exceptionally wet summer and the wettest three months on record,” he said.

Fowler said that Auckland already had a wet January before the storm on the 27th, but that event doubled the total in a single day.

“Rainfall intensities in the early evening, at the height of the storm, were quite astounding,” he said.

On January 27, Auckland’s Albert Park was drenched with 280mm of rain in under 24 hours and 211mm in under six hours. The falls led to widespread flooding across the city.

Niwa weather has described it as at least a one-in-200-year event.

In total, central Auckland experienced over 45 per cent of its yearly rainfall in the month, with the annual average being 1190mm. This is more than 8.5 times that of a typical January and more than 2.5 times a usual entire summer.

Niwa meteorologist Ben Noll said that elements came together in a “perfect storm” to cause the unparalleled deluge.

“A slew of environmental factors contributed to this extreme event - a formidable La Niña and marine heatwave led to more moisture being available, which was harnessed by an atmospheric river,” Noll said.

Flooding at Auckland Airport on January 27. Photo / Pamela Mills, Twitter

“High pressure to the south then blocked it, keeping it in place. The storm was also supported by unique phenomenon called a low-level jet, as well as converging winds that extended lengthwise across the most populated part of the country.

“All of these factors leveraged the atmosphere’s tremendous moisture content to drop an entire summer’s rain in less than a day. And if it sounds complex, that’s because it is - extreme events occur under extreme circumstances.”

Niwa climate scientist Dr Sam Dean says the influence of climate change made the event more intense.

“The earth has warmed by about 1.1C already because of human activity and this extra heat gives more power to extreme rainfall. All other things being equal, we would expect climate change to contribute between 10-20 per cent more rain in the most intense part of this storm,” Dean said.

“This feeds into a proportionately larger effect on the extent and depth of flooding, causing more damages and costs. It’s imperative to consider whether climate change has increased the likelihood of the storm’s precursor conditions occurring again.”

Rain across Auckland resulted in widespread flooding and extensive damage. Four people lost their lives; Dave Young in Onewhero, Daniel Mark Miller and Daniel Newth in Wairau Valley, and Dave Lennard in Remuera.

There are 95 teams out assessing homes today and to date, there have been 195 red stickers issued, 971 yellow stickers issued and 1807 white stickers issued.

Auckland Transport’s Stacey van der Putten said so far approximately 1500 flood-damaged cars have been towed across the city.