New Zealand is officially in an El Niño, and the forecasters who declared it think this one could turn out to be among the strongest ever measured.
Earth Sciences New Zealand, the government science agency formed last year by merging NIWA with GNS Science, confirmed the event on Wednesday in its latest seasonal climate outlook. It follows similar declarations from weather agencies in Australia, Japan and the United States, which all watch the same slab of the tropical Pacific Ocean for the tell-tale warming that drives the pattern.
Principal scientist Chris Brandolino did not hedge on how big this one might get. He told RNZ the event would “at the very least rival the intensity of the five strongest El Niño events already on the modern record”. He went further than that. “There are compelling reasons to believe it will exceed that, and it has all the makings to be an historically strong event,” he said.
El Niño is one half of a natural see-saw in the Pacific that scientists call the El Niño Southern Oscillation. In an El Niño year the trade winds that normally push warm water and rain towards the western Pacific weaken, and a large pool of warmer than usual water spreads east along the equator. That shift ripples out through the atmosphere and rearranges weather patterns far from the tropics, including here at the bottom of the world.
For New Zealand the textbook signature of a strong El Niño is more wind from the west and southwest, a drier eastern side of both islands, and wetter conditions in the west and south. Brandolino said the coming spring looked set to follow that script, with drier than usual weather across most of the North Island and down the east coast of the South Island, and a windier spring for many places. Southland and the lower West Coast, by contrast, are expected to catch more rain than normal as those westerlies pile moisture up against the ranges.
The heat side of the picture is less tidy. Brandolino described the temperature outlook as “spiky”, the sort of season that can deliver a run of unusually warm days without settling into a steady baking. He was careful to say New Zealand was unlikely to see anything like the 40 to 44 degree extremes that have scorched parts of Europe, but warm spells are on the cards.
Part of what makes forecasters cautious is that no two of these events behave exactly alike. “Every El Niño event has its own fingerprint, its own personality,” Brandolino said. The label tells you the broad direction of travel. It does not tell you precisely which week the wind will turn or which district will miss out on rain.
The declaration lands at an awkward moment for the drier half of the country. Canterbury and parts of the eastern South Island are already in what the agency called a meteorological drought, which Brandolino noted was “really remarkable” for the middle of winter, a season when those areas would normally be topping up their soils and catchments rather than running them down. A significant rain event expected in the following week should “help take the edge off”, he said, but a single front does not undo a dry winter, and an El Niño spring is the last thing a parched east coast wants to see coming.
That matters well beyond the weather map. The eastern plains of both islands carry a large share of the country’s sheep, beef and arable farming, and a dry spring can mean thin pasture, early culling decisions and pressure on irrigation just as demand ramps up for summer. Dry, windy conditions also lift the fire risk heading into the warmer months, the same combination that has fed some of the country’s worst rural blazes. Water storage and hydro generation are exposed too, because the lakes that drive much of the national grid sit in catchments that El Niño tends to treat unevenly.
None of that is a forecast of disaster. El Niño is a probability shift, not a guarantee, and the west and south of the country may well end the season greener than usual. But the pattern does tilt the odds, and a strong event tilts them harder. As Brandolino put it, “when we have these strong or very strong so-called Super El Niños, we tend to find stronger impacts or more profound impacts”.
The seasonal outlook covers the months ahead through spring and into summer, and Earth Sciences New Zealand updates it as the ocean and atmosphere show their hand. For now the message is straightforward enough. The Pacific has flipped, the flip looks like a big one, and the parts of New Zealand that have grown used to dry easterly seasons should plan for another, possibly a severe one.
For anyone on the land, on a tank supply, or simply weighing up whether to fill the water butt before spring, it is worth keeping an eye on the fortnightly updates rather than reading too much into any single sunny week. The overall shape of the season is what counts, and this season’s shape is now a lot clearer than it was a week ago.
Are you a farmer, grower or gardener already feeling the dry in the east, or bracing for a wet one in the south? Tell us what you are seeing where you are 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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