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A map of rainfall in NZ over two summers (Maps: Chris McDowall)
A map of rainfall in NZ over two summers (Maps: Chris McDowall)

ScienceFebruary 20, 2023

A climate tale of two summers

Contributing writer
A map of rainfall in NZ over two summers (Maps: Chris McDowall)
A map of rainfall in NZ over two summers (Maps: Chris McDowall)

Three years ago, the North Island experienced droughts while the South Island flooded. This year, it’s the opposite. 

In January 2023, Auckland experienced its wettest month on record. The heaviest rains occurred on the evening of January 27 when the city received a deluge that overwhelmed stormwater systems and resulted in widespread flash flooding. Over 24 hours, the Albert Park weather station recorded 280 mm — more rain than it typically receives over an entire summer.

Cars floated down suburban streets. Already sodden hills slipped and collapsed into buildings. Homes and businesses filled with water. Rivers changed shape. Four people died. Countless pets and other animals were lost. Emergency responders were superhuman.

Flooding in Wynyard Quarter, Auckland. (Photo: Lynn Grieveson/Getty Images)

Cyclone Gabrielle arrived two weeks later. Once again Northland, Auckland, Coromandel and Bay of Plenty experienced flooding, this time accompanied by gale-force winds. Tairāwhiti and Hawke’s Bay suffered its worst effects and the true extent remains unclear. Half a million people without power. Ten thousand people displaced. The government declared the third national state of emergency in New Zealand’s history. Burst floodbanks, landslides, flooded homes, rooftop evacuations, communication outages and death upon death. 

One fucking disaster after another.

Throughout these events my mind keeps returning to a climate change documentary series I worked on with the Spinoff in 2020 called 100 Year Forecast. Specifically, I think about the opening lines of episode two, “Where New Zealand will get wetter and drier”.

“February 4th, 2020. Auckland is in the midst of a big, long dry. No rain has fallen for 21 consecutive days. The very same day in Fiordland so much rain is pouring from the sky a state of emergency is declared. […] One country; two hydrological extremes.”

In February 2020, Aotearoa experienced extreme contrasts between Te Ika-a-Māui North Island and Te Waipounamu South Island. The lower South Island had record-breaking rainfall. This led to a state of emergency declared in Fiordland and Southland, as flooding and landslides forced many to evacuate. This was the largest aerial evacuation in New Zealand’s history, with over 700 people evacuated from the affected areas.

While the south grappled with extreme weather conditions, much of the north faced severe drought. A week after the Fiordland and Southland emergency evacuations, the government declared drought in Northland and parts of Auckland. Months of low rainfall had led to water shortages and crop failure. The situation became so severe that the New Zealand Defence Force was sent to Northland towns to assist in drought relief efforts.

This map shows the north in drought and the south experiencing extremely wet conditions.

Extremely dry weather in the north; deluges and flooding in the south.

Three years on the situation has flipped. As Te Ika-a-Māui endures devastating rainfalls, much of Te Waipounamu has experienced record dry weather. During January 2023, 18 South Island locations observed record or near-record low rainfall totals.  Invercargill had its driest January since records began in 1900. Wānaka recorded just 4mm of rain for the whole month.


While climate change cannot be blamed for the existence of Cyclone Gabrielle or a prolonged absence of rain, the scientific consensus is that human warming intensifies these events. We are making everywhere slightly warmer. With every degree of warming, the atmosphere can hold more moisture. A bigger bucket means heavier downpours. But we do not know quite where that water will fall from year to year — just that the future is likely to hold more extreme events as we keep breaking temperature records.

I keep thinking about the contrasting summers of 2020 and 2023. And atmospheric science. And the land. And all those affected. And heartbreaking stories. And the nature of media coverage. And the state of our infrastructure. And the role of policy. And the future of insurance. And action and inaction. And injustice.

Round and round and round.

The complexity makes me realise that I have a cartoon vision of climate change in my head. Dim notions of buckets, greenhouses, thermostats and canaries in coal mines. Metaphors that I mistook for knowledge. They help, but they are not the thing.

Humans have a tendency to avoid uncomfortable truths, whether they’re about the environment, our mortality, or some other difficult aspect of life. The first time I seriously engaged with the prospect of climate change was as a geography undergraduate in the 1990s. Since then I have often worked with environmental scientists and science communicators, getting exposed to the science and implications of climate change.

A car submerged in floodwater near Napier, February 16, 2023. (Photo: STR/AFP via Getty Images)

Despite all those conversations, lectures, graphs and maps, I have not internalised what a changing climate means. I recognise difficult things will come to pass; yet I do not feel the scale and urgency of the issue. Not truly. Not enough.

Staring at maps of February 2020 and January 2023 as gale-force winds bend the oak outside and the radio shares stories of drowning livestock makes the need to reduce carbon emissions feel urgent. But when the sun comes out and the water recedes, urgency risks fading into complacency. It’s a tricky needle to thread. We need to find ways to collectively hold onto our situation's gravity, without becoming overwhelmed and giving up.

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Seeking guidance, I turned to the final episode of 100 Year Forecast. In the closing moments, environmentalist and iwi leader Mike Smith (Ngāpuhi, Ngāti Kahu) draws a comparison with the early Covid-19 response.

“Just imagine what would have happened if we had two years lead-in time to prepare for Covid-19 – how different things would have been. With climate change we do have that lead-in time. We do have the opportunity to plan for it. And we do have the opportunity to take action.”

More Reading
Without a database to track losses from weather disasters, we’re planning in the dark How can we talk about disaster risk management and risk reduction when we have no idea what's going on?
Climate change, community, kai: How extreme weather impacts Māori food systems Kai sovereignty is all about reclaiming the relationship between communities and their local food. But is that actually possible in the aftermath of a devastating cyclone?

These words give me hope. There will be more devastating environmental events. But there is still time to act and limit their severity. The actions needed are straightforward. Reduce your personal emissions. Reduce consumption and waste. Talk about climate change with the people in your life. Demand action from elected representatives.

There is still time to act. We should act.

Keep going!
A disastrous drought and a ferocious flood side by side.
A disastrous drought and a ferocious flood side by side. (Images: left RNZ, right Hawkes Bay Civil Defence)

ScienceFebruary 17, 2023

The wet-dry flip-flop

Climate writer
A disastrous drought and a ferocious flood side by side.
A disastrous drought and a ferocious flood side by side. (Images: left RNZ, right Hawkes Bay Civil Defence)

Three summers ago the north of New Zealand was in drought while Southland suffered floods. This summer, we’ve got the inverse. What’s going on?

This is an excerpt from our weekly environmental newsletter Future Proof brought to you by Electric Kiwi – sign up here.

With the north drenched to its core by so much rain, it’s easy to forget that just a couple of summers ago we were in the midst of a drought. Aucklanders were being urged to conserve water as dam supplies dwindled and Northland farmers were forced to cull stock. Meanwhile, Southland was ravaged by floods and landslides.

This summer, the situation is inverted, with dry heat in the south and way too much wet in the north. Data journalist Chris McDowall, who looked into which areas of New Zealand are likely to become wetter and drier as part of The Spinoff’s 2020 series 100 Year Forecast, wondered what was behind this wet-dry flip-flop. So I asked Sam Dean, Niwa climate scientist.

A dried up Auckland dam during the 2020 drought.
A dried up Auckland dam during the 2020 drought. (Photo: Watercare)

‘Blocking high’ behind north-south pattern

The “north-south dipole” is a pattern that’s often seen in New Zealand, says Dean. “When you analyse rainfall, it’s one of the primary patterns that comes out — but it’s not the only pattern. Just because it’s wet in the north doesn’t guarantee it’s dry in the south.”

Dean explains that behind this flip-flop, a bunch of large scale systems align to create “blocking highs” — including the depletion of the ozone layer, which has shifted regular storms poleward, encouraging highs to form above New Zealand. Exactly where these high pressure systems sit determines who gets wet, and who stays dry. This year, the forces of La Niña and other regional climate cycles have led to a blocking high off the east, which has opened the door for rainfall-bearing systems like the ex-tropical cyclone to bear down on the north. “The cyclone is being affected by this high pressure east of the country: it’s got nowhere to go, and has become very slow moving. This increases the damage because it goes on for longer, rather than nipping by,” says Dean.

Will we see more cyclones as the climate changes?

On average, we see one ex-tropical cyclone pass close to New Zealand every summer, and Dean says we don’t have any evidence that this number will increase. But as the climate warms, “there’s more fuel for them when they do happen — more heat, more moisture — so they can have stronger winds and more intense rainfall.”

People wait for a rooftop rescue (Photo: Royal New Zealand Air Force)

Averages mask the extremes

Looking at 100 Year Forecast’s seasonal maps, you can see which regions will get wetter or drier on average. But what these seasonal averages mask are the extreme events that will define our climate future; the flip-flops between drought and downpours. “Models suggest that short duration flash flooding — like we saw in Auckland in January — is going to increase the most under climate change,” says Dean. “Also, Northland and Auckland will see the biggest increases. That part of the country is becoming distinctly more variable.”

While the models predict that severe rainfall will become more intense and more frequent, the “off-the-charts” events like Auckland’s floods pose a challenge for scientists when it comes to understanding how they form, and how they’re affected by climate change. “We are embarking on a crazy experiment, fundamentally terraforming the planet into a different kind of place. And there are massive risks associated with that,” says Dean. “We don’t necessarily have a good understanding of how some of these most extreme events are going to behave when you give them that much more energy to work with.”

January flooding in downtown Auckland. (Photo: Sarah Brady)

While such extremes are scary, Dean emphasises that New Zealand will always be relatively habitable compared to many places around the world. “As long as things aren’t changing too fast, then people are really adaptive,” he says. “The more we can slow the changing climate, the better chance we have to adapt.”

And for those impacted by the current devastation: “I just hope for those people that they can rebuild their lives and find a way to be safe in a changing climate.”