[11] In January 2023, Auckland and the upper North Island experienced relentless maritime heatwave conditions caused by the annual La Niña cycle and exacerbated by climate change.

[18][19] From 27 January, a tropical atmospheric river carrying a long band of rain and thunderstorms lay mostly stationary over the upper North Island, blocked by a large anticyclone to the southeast of the country which prevented it from moving south across New Zealand.

[9] This atmospheric river was brought down into the New Zealand area by the remnant low left behind by Tropical Depression 06F, which moved south into the Tasman Sea.

[25][20] January 2023 was declared the wettest month ever in central Auckland by NIWA, with the total of 539 millimetres (21.2 inches) surpassing the 420 mm (17 in) recorded in February 1869.

[29] After the heaviest rains subsided, the risk of landslides in Auckland and across other areas of the North Island persisted due to the extreme amount of water in the soil.

[34] On 28 January, the Interislander ferry MV Kaitaki lost power while sailing between Picton and Wellington in Cook Strait at around 5:00 pm.

[44] The flooding in Auckland on 27 January affected 25 suburbs in the city, closed major motorways, and left 6,000 to 8,000 homes in need of damage assessment.

[10] Mayor of Auckland Wayne Brown stated that over 200 lifts were reported to not be working across the city after the floods, potentially isolating elderly residents at the top of apartment buildings, but Age Concern Auckland CEO Kevin Lamb stated that they had not had any calls about elderly people experiencing difficulties because of lift outages.

[51] A second event in Auckland on 1 February resulted in several homes, businesses, and roads being inundated by flooding, with major slips being reported.

[53][54] AA Insurance stated that the floods were its largest vehicle claims event in history,[55] with an estimated 10,000 cars expected to be written off.

[56] The event also surpassed the total cost of NZ$351 million of weather-related insurance claims in New Zealand during the entirety of 2022, which was previously the highest number in a year ever.

[61] On Saturday 28 January, severe flooding in the Waitomo District of the Waikato region resulted in many evacuations, particularly around the town of Te Kūiti.

[10] By 11:36 pm on Friday 27 January, Auckland Transport had announced multiple road closures due to slips, flooding, tree clearing, and storm damage.

[65] As of 12:21 pm on Sunday 29 January, 700 homes across Auckland were still without power, while residents of western suburbs were left without water after a slip caused 30 metres of pipe to be washed away in Titirangi.

[70][6] A Qantas flight bound for Sydney with 200 passengers aboard was stuck on the tarmac, unable to move or be evacuated, with all of its occupants having to stay there overnight.

[74] Kelly Tarlton's Sea Life Aquarium[75] and several chain-owned supermarkets were closed due to extreme flooding on 28 January.

[79] Auckland Zoo was also affected and major flooding occurred in lower-lying areas, after animals like American alligators, bearded dragons and skinks had to be evacuated to higher ground; a kōtare and a zebra finch died, and their bodies were recovered.

[81] On Monday 30 January, The Ministry of Education had advised all 557 schools, numerous universities, polytechs and early childhood care centres across the Auckland Region to be closed until Tuesday 7 February for further damage assessment.

[27] The Friday night Elton John concert, which 40,000 people were expected to attend, was cancelled shortly before it was due to begin, after 11,000 concert-goers had already arrived.

[89] After suffering repeated flooding events in August 2021, March 2022, January 2023, and later February and May 2023, a widespread sense of collective trauma emerged across the Auckland region.

[91] Residents who had been flooded multiple times reported feeling symptoms of PTSD during periods of rain, including not being able to sleep at night in anticipation of the following day's weather forecast.

[96] The New Zealand Defence Force provided assistance in the flood recovery and clean-up,[97] as did the Student Volunteer Army and the Red Cross.

[98] On Saturday 28 January, a state of local emergency was declared in the Waitomo District in the Waikato region after significant flooding, which was rescinded on Monday 30 January,[27][90] while on Friday 3 February, a state of local emergency was declared in the Thames-Coromandel District in response to slips in the area blocking crucial roads and isolating communities.

[99] On Thursday 9 February, the states of emergency in place in Auckland and the Coromandel were extended in anticipation of Cyclone Gabrielle impacting the country.

[110] Brown declared a state of emergency immediately after the AEM advised him to do so, hours after the extreme weather began, but was widely criticised for his response, which was said to show hesitation and a lack of presence.

[120] Transport agency Waka Kotahi was criticised after staff responsible for providing updates during the event clocked off for the holiday weekend at 7:30 pm on 27 January while many roads across Auckland were flooding.

After the agency's chief executive was spoken to by Deputy Mayor of Auckland Desley Simpson, group manager of parking services and compliance John Strawbridge said all fines issued between 2:00 pm on Friday and 9:00 am on Wednesday 1 February would be waived.

The group's formation was in response to hundreds of homes in West Auckland being yellow and red-stickered, rendering them uninhabitable as a result of flood damage.

[126][127] In February 2023, the Government confirmed that it was designing a managed retreat strategy for those who lost their homes as a result of the Auckland Anniversary Weekend floods and Cyclone Gabrielle.

[127][128] In early October 2023, the Auckland Council voted unanimously to accept a proposed cost sharing arrangement with the Government to fund over NZ$2 billion in flood recovery and resilience works.