New Zealand has declared a state of emergency in its capital, Wellington, after a storm dumped a record 77 millimetres of rain in under an hour in the early hours of Monday morning — nearly three times the heaviest rainfall the city has ever previously recorded in a single event. Mayor Andrew Little, who said he lay awake through the night sensing the severity of what was coming, described the deluge as not merely heavy but "very heavy, and lasting a long time." More than a dozen people have been evacuated, around 30,000 homes across the North Island lost power, and a 60-year-old man remains missing, with a large search operation underway. Flights to and from Wellington were cancelled en masse.

The impacts across the city were severe and immediate. Streets filled with mud, cars were swept away by floodwaters, underground car parks were inundated, and trees were uprooted. Landslides damaged homes in surrounding areas. Wellington's hospital was temporarily cut off by floodwaters before access was restored. One 87-year-old woman sought refuge at the top of her wardrobe as water rose through her home. Emergency services — including the fire brigade, which had been set to go on strike that day — received close to 900 distress calls. Hubs were established in Lower Hutt, a suburb in the wider Wellington region, to shelter displaced residents.

Meteorologists have pointed to a combination of factors that made this "ordinary" Southern Ocean low-pressure system produce extraordinary results. Cold air moving over unusually warm Tasman Sea waters generated intense clusters of thunderstorms, while converging winds along Wellington's south coast forced moisture sharply upward and held the heaviest rainfall over the same areas for prolonged periods. Because the storm followed Cyclone Vaianu — a tropical system that had struck the North Island just a week earlier — the ground was already saturated, meaning even a less extreme event could produce severe flooding. Forecasters had identified the risk of severe weather in advance, but the precise locations of the heaviest downpours are extremely difficult to predict at the fine scale where outcomes are determined. Further heavy rain, potentially reaching 100 millimetres and up to 250 millimetres in nearby ranges, along with thunderstorms and strong gusts, is forecast in the coming hours. Residents in flood-prone areas have been advised to move to higher ground.

Scientists note that while no single storm can be attributed to climate change in isolation, the event reflects a broader and accelerating pattern. As ocean and air temperatures rise, the atmosphere holds more moisture, providing additional fuel for intense, short-duration rainfall. New modelling by researchers at the University of Waikato projects that even under a mid-range emissions scenario, the most intense rainfall events across much of New Zealand could increase by 10–20% by the second half of this century. Experts warn that even seemingly modest increases in intensity can push infrastructure past critical thresholds, turning manageable floods into disasters. Wellington's last comparable catastrophe, the 1976 storm, cost tens of millions of dollars; the bill for Monday's event is still being calculated.