Parts of Aotearoa may face water shortages and increased wildfire risks this spring, Earth Sciences NZ says.
El Niño has been declared in the tropical Pacific, and is expected to intensify into one of the strongest on record.
This is likely to cause increasingly dry conditions in eastern and northern areas of the country over the next few months, while more rainfall is expected in the south and west of the South Island.
The SMC has gathered comments from experts on:
- Weather modelling (2 comments)
- Agriculture and the economy (1 comment)
- Plants and animals (1 comment)
- Wildfires (2 comments)
- Drought (1 comment)
- Groundwater (1 comment)
Weather modelling
Dr Nathanael Melia, Founding Director of the Independent Research Organisation Climate Prescience Limited and Adjunct Senior Research Fellow as Victoria University of Wellington, comments:
“El Niño — ‘the Christ child’ — was named by Peruvian fishermen for the warm water arriving around Christmas. For their fisheries and society it was bad news: the trade winds weakened, sometimes reversed, and the cool, nutrient‑rich water that normally upwells along the equatorial west coast of South America vanished — and the fish went with it. That local event is the fingerprint of the largest natural cycle in our climate system, the El Niño Southern Oscillation (ENSO), in which Pacific conditions flip between warm (El Niño) and cool (La Niña) every few years.
“Seasonal prediction is fraught. Early calls for any El Niño — let alone the ‘historic’ ones filling headlines since Christmas — are hyperbole, because forecasts made before the autumn predictability barrier carry little skill. We are past it now, and the major centres agree we have an El Niño. But its strength, and what it means for New Zealand, are far from set.
“Picture our weather as a pantheon. ENSO is Zeus; El Niño is his temper this year (and he is in a rile). Beneath him, the gods of ocean and atmosphere must agree before El Niño takes hold (which they have), then pass their intentions to lesser deities setting the mood near New Zealand, who whisper how each week should look. Right now for example, one lesser god — a near‑record positive Southern Annular Mode — is pushing the westerly storms south, and may delay El Niño’s grip.
“At every step the local signal can be modified or lost — more uncertainty than the ESNZ press office headline admits. The respected global centres signal a most‑likely strong event, with a real chance — but no certainty — of very strong at its peak; none lead with ‘record’. However, even then cooler heads are needed as climate change already tilts the crude El Niño temperature metric high, while the centres’ confidence and signals are self‑referential forecast consensus, which can differ from the climate’s true uncertainty.”
Conflict of interest statement: “No COI.”
Troy Baisden, co-President of the New Zealand Association of Scientists and Adjunct Professor at Victoria University of Wellington, comments:
“Earth system models have settled on consistent indications that this will very likely be the strongest El Nino ever – so much so that historical understanding of strong El Nino effects may not be predictive for this year. These are exactly the conditions where it would have been desirable to have the strength of modelling and assessment teams for our unique corner of the Earth that were defunded and dispersed recently, by the end of support including the Deep South Challenge (see here for more details).”
Conflict of interest statement: “No conflict of interest.”
Agriculture and the economy
Professor Anita Wreford, applied economist, Lincoln University, comments:
“The declared El Niño conditions could have important implications for Aotearoa NZ’s agricultural sector and the wider economy. Typically El Niño conditions have led to droughts in the eastern parts of the country – the impact of these will depend on how long they last and how widespread across the country they are. Drought conditions negatively affect agricultural production, often requiring supplementary feed to be purchased, the culling of stock and potential tension between different users of water.
“Previous El Niño events have led to a reduction of 0.4% of GDP after four quarters 1 (following a relatively standard El Niño event, not an intense one like this one may be). In context, Aotearoa’s real GDP grew by 0.2% over the 2025 calendar year, so the impact is not insignificant.
“The financial impact depends also on whether and how El Niño presents globally, as Aotearoa is highly connected globally through trade. If other agricultural producing countries are negatively affected, this could reduce global supply and result in higher global prices for commodities such as dairy. This would soften the impact for our producers, but consumers would end up paying more for affected food items. In addition, if El Niño affects the supply of some of our imported feeds, these prices will also increase, affecting our livestock producers.
“Direct impacts on the agricultural sector flow into other areas of the economy, including processing, transport, business and the regional economies. If reduced rainfall in key areas affects hydropower storage, electricity prices will increase and affect all users of electricity. Wildfire risk would also increase, particularly as strong winds are expected alongside drier conditions.
“The impacts are currently uncertain, but exposed sectors can reduce the risk by having robust and flexible plans to adjust their practices as the impacts unfold.”
Conflict of interest statement: “No conflicts.”
Plants and animals
Professor Cate Macinnis-Ng, School of Biological Sciences, University of Auckland, comments:
“From a biodiversity perspective, the likely drier spring conditions across much of the country can bring mixed impacts. If dry conditions continue for several months, especially if they remain into the warmer summer months, trees, other plants and animals will start to suffer water stress. This can reduce plant productivity, reducing carbon uptake. As drying ground hardens, kiwi are unable to penetrate the soil to access their food. Similarly, mudfish suffer during dry summers as the forest pools they live in dry up quickly.
“However, there can be some early positive effects. The strong relationship between El Niño conditions and growth of kauri trees is well known. Analysis of tree-rings of kauri indicates wider rings during dry springs associated with past El Niño events. This is possibly because the trees are more productive when there is less cloud cover but the physiological mechanism behind the growth has not been fully explored.
“Overall, the longer a drought lasts, the worse the impacts will be and when drought coincides with warmer and drier air, drought impacts will also be worsened. High winds are likely to bring down branches and topple trees, potentially creating fuel for fires. Drier vegetation (dead or alive) becomes more flammable, and together with warm and windy conditions, these factors all further increase fire risk. In parts of the country where rain will increase, biodiversity will suffer from the impacts of flooding and land slides which can be equally damaging as the impacts of dry conditions.
“The seasonal climate outlook released by Earth Sciences New Zealand emphasises the complexity of weather during coming months. It will be interesting to see how the coming seasons play out and understand that if the worst scenarios don’t occur this summer, they are our new reality. While El Niño conditions are a natural part of the weather cycle, extreme events are being intensified by climate change. We desperately need to better prepare for these extremes rather than responding to crises as they happen.”
Conflict of interest statement: “I am Lead Author for the Intergovernmental Panel on Climate Change Assessment Round 7 Working Group 2 but these comments are my personal professional opinion.”
Wildfires
Shana Gross, Fire Ecologist, Bioeconomy Science Institute, comments:
“Wildfires occur across all phases of El Niño Southern Oscillation (ENSO), but the phase alone does not mean there will be a greater number of fires or greater number of areas burnt. None of the years identified as strong El Nino events (1991, 1997, and 2015) have particularly high area burnt or number of wildfires. However, the year following 1997 (1998/1999 fire year) was the worst on record for area burnt.
“An important caveat is that El Nino is also the most infrequent phase of ENSO. Between 2000-2020 there have been fewer fires and less area burnt during El Nino, but it has also been the most infrequent phase.
“The weather is what we need to focus on. Fire weather can occur during any of the phases. Key things to be aware of are dry conditions where fuels can ignite and high winds where fire can spread. So, where El Nino brings dry and windy conditions, fire hazard will increase. During these periods it is critical for the people to be aware of heightened fire danger and be cautious with activities to avoid ignitions. Wildfires will happen if ignitions happen.”
Conflict of interest statement: “No conflict of interest.”
Veronica Clifford, Senior Technologist in the Wildfire Research Team, Bioeconomy Science Institute, comments:
“With the prediction of a strong El Nino appearing in the horizon, a helpful guide is this monthly fire seasonal severity poster, where you can get a rough idea of how things panned out across the country for each of the past El Niño Southern Oscillation (ENSO) phases during our fire seasons.
“Under El Niño there are increased odds for severe fire danger in regions that experience conditions that are warm, windy, and drier than usual. Those regions are generally located in the north and east of both islands.
“To help understand what the upcoming fire season could look like, recent past events reminiscent of a strong El Niño included 2015/16, 2009/10, 1997/98 and 1991/92. These years are potentially good indicators for what to expect this coming fire season.
“We can clearly see from significant historical El Niño events that no two El Niño’s produce the same outcomes. In general, under El Niño, there is an increased likelihood of elevated fire danger in the north and eastern regions of both islands (you can see the hotspots in the red areas). The effects of a strong El Niño can be seen as early as November and can linger into March/April. This warrants early fire risk management discussions and actions by landowners and managers whose livelihoods are likely to be affected by prolonged dry, warm, windy conditions generated by El Niño events.”
Conflict of interest statement: “I’m not aware of any conflicts of interest.”
Drought
Dr Luke Harrington, Senior Lecturer in Climate Change, The University of Waikato, comments:
“We often see quite strong reactions to the declaration of an El Niño event here in Aotearoa, perhaps with less justification than for other parts of the world. Keep in mind that some of our biggest droughts, including 2012/13, 2007/08, 2000/01 and 1988/89, all occurred during either ENSO neutral or La Niña conditions.
“However, it is also reasonable for certain parts of the country to pay attention to the potentially elevated risks of dry weather over the coming months – particularly the east coast of the North Island. Yes, we have good memories of 1997/98 and perhaps also 1982/83 and 1972/73. But the biggest warning signs I’d point to are the risks of significant dryness before the summer has even arrived.
“The 1994 Auckland water crisis was arguably driven by an incredibly dry period between July and October 1993 (a weak El Niño event, depending on who you ask). And if we look further back in time again, the second half of 1914 was simply unprecedented when it came to the protracted lack of rainfall over the entire North Island. If we saw that sort of El Niño event happen again today, it would be a wake-up call as to how vulnerable to drought we can be in this country.”
Conflict of interest statement: “No conflicts.”
Groundwater
Dr Helen Rutter, Senior Hydrogeologist, Lincoln Agritech, comments:
“Water makes its way into the groundwater system mainly during the winter when temperatures are lower, plant growth is limited, and any rainfall may infiltrate through the soil and not be used up by plants. The report suggests that below-normal winter rainfall in several regions (if it occurs) may mean we get below normal groundwater recharge, and this could become an issue for people who use groundwater for drinking water, irrigation or other uses.
“The implications of low recharge this winter will depend on how healthy the groundwater reserves are currently. Groundwater levels vary with season, and from year to year. Where groundwater levels are already low, if there is reduced winter recharge, then this could affect people’s ability to abstract groundwater, though the effects may not be felt until next summer. If groundwater levels are currently high, then the effects of a low recharge winter are usually not as severe in terms of being able to access and use groundwater.
“It is important to note the caveats stated: the report assesses the likelihood of climate conditions being at, above, or below average for the season as a whole and are not ‘weather forecasts’. (It is not possible to forecast precise weather conditions three months in advance). Additionally, they are the result of expert judgment of scientists and forecasters. The forecasts are not actual impacts in terms of local weather through the winter, which will only be known as they eventuate.”
Conflict of interest statement: “No conflict of interest.”