New Zealand’s climate forecasters say the tropical Pacific is building towards what could become one of the strongest El Nino events ever recorded, with the country’s already parched eastern regions facing the greatest risk of drought and wind through the rest of the year.
Earth Sciences New Zealand, the Crown research institute formerly known as NIWA, says warm water has surged eastward beneath the surface of the equatorial Pacific in recent months and the ocean has flipped from cool to warm at a remarkable pace. A formal declaration of El Nino is expected within weeks, and forecasters in Australia, Japan and the United States have already called it.
Chief weather scientist Chris Brandolino told RNZ the signs point to something well out of the ordinary. “It is distinctly possible that this El Nino may comfortably exceed the previously high-end El Nino event,” he said. “While we’re pretty confident we will see something quite extraordinary, potentially unprecedented in terms of El Nino strength, we’re not quite so certain that those impacts will follow suit here in New Zealand.”
El Nino is one half of a natural climate cycle in the Pacific known to scientists as the El Nino Southern Oscillation. It is not a new phenomenon and it is not the same thing as long term climate change. Every few years the trade winds that normally pile warm water up in the western Pacific weaken, and that warm water sloshes back east towards South America. That shift changes where storms form and rain falls, and the effects ripple right around the globe, including down to New Zealand.
What has forecasters paying close attention this time is the scale of the warming. Brandolino said a very strong El Nino, sometimes called a super El Nino, is reached when ocean temperature anomalies in the central Pacific hit or pass two degrees Celsius above average, and this event is forecast to comfortably exceed that mark. Some models are pointing to anomalies of more than three degrees. The central Pacific has already swung from about one degree below average in January to around seven tenths of a degree above average now.
If the forecasts hold, the 2026 event would rival or surpass the five strongest modern El Ninos, those of 1972 and 1973, 1982 and 1983, 1992 and 1993, 1997 and 1998, and 2015 and 2016. The strongest of those reshaped weather across the Pacific and were felt keenly in New Zealand farming and water supplies.
For New Zealand the typical El Nino pattern is fairly well understood. More frequent westerly and southwesterly winds tend to drive rain onto the western and southern flanks of the South Island, while the east of both islands and the upper North Island turn drier and windier. Earth Sciences New Zealand’s seasonal outlook puts the chance of El Nino conditions emerging over the June to August window at about 95 percent, with the peak of the event expected over the summer of 2026 and 2027.
That timing matters because parts of the country are starting from a dry base. Brandolino said Canterbury, already in meteorological drought, is especially exposed. “They’re already on the back foot,” he said. The eastern South Island has little moisture in reserve to cushion a dry spring and summer, which raises the risk of water restrictions, stressed pasture and a longer, sharper fire season. The upper and eastern North Island may get some temporary relief from higher ground moisture, but a strong El Nino summer would test irrigation and stock water across the drier east.
Forecasters have been careful to separate confidence about the ocean from confidence about exactly how it lands on the ground here. A strong El Nino loads the dice towards a drier east and a wetter southwest, but it does not guarantee any single season, and short bursts of cold southerly weather can still punch through even in a warm El Nino year. Earth Sciences New Zealand has said it will firm up its picture as the event develops over winter, with its forecasters noting that the early development closely tracks the way the powerful 1997 event began.
For now the message from the science agency is to watch and prepare rather than panic. Farmers in the east are being encouraged to think early about feed and water budgets, councils about supply and fire planning, and households about how a long dry stretch might play out where they live. The next few months will show whether the Pacific delivers the record some models are now flagging, and how much of that reaches down to New Zealand paddocks, rivers and reservoirs.
Have you been through a tough El Nino summer before, on the land or in town? Share what you remember and how you are preparing this time in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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