Wellington, New Zealand floods: expert comment

Professor Hannah Cloke comments on the flooding in Wellington, New Zealand, after a state of emergency was declared. 

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Professor Hannah Cloke said: "In Wellington, intense downpours have led to widespread flash flooding. This heavy rain has fallen on top of that from Cyclone Vaianu a week earlier, which meant soils and catchments were already saturated like a wet sponge. Rivers have done what they always do, which is to overflow their usual banks and spread out across floodplains. Unfortunately, in some parts of Wellington, these areas are where people have homes, roads and infrastructure. This means streets and low-lying neighbourhoods suddenly become part of the river.

"For those affected, the experience is sudden, dangerous and disorienting. Homes, shops, and businesses are damaged by the violent force of moving water, leaving behind a tidemark of disruption that lingers long after the flood itself retreats. 

"What we are seeing here is caused by extreme downpours of rain and weather patterns, which we know are being shifted by changes to our climate, caused by human activity. A warmer atmosphere acts like a bigger, wetter reservoir in the sky, loading storms with more water. When it falls, the water arrives harder, faster, and with greater consequences for people living in the way."

Professor Liz Stephens said: "The floods in Wellington were caused by a lot of rainfall falling in a short period of time, with reports suggesting record rainfall over the city. This intense rainfall can quickly overwhelm drainage systems, causing flash flooding and landslides. Evidence from events like the European floods of 2021 and the Valencia floods of 2024 shows that when rainfall is truly unprecedented, people often struggle to anticipate the scale of impacts.

"New Zealand has some of the most advanced, high-resolution weather forecasting models in the world, but even these models cannot pinpoint exactly where the worst rainfall will hit. This uncertainty makes it challenging to issue highly targeted, timely early warnings for the communities at risk."