New Zealand is on the cusp of one of the most significant climate shifts in years, with the country’s national forecaster warning that a powerful El Nino is building in the tropical Pacific and could grow into one of the strongest events on record. Earth Sciences New Zealand, the organisation that now houses NIWA, says the coming winter may mark the start of a formidable El Nino that reshapes rainfall, wind and temperature patterns across both islands.
The forecaster’s latest seasonal climate outlook puts the chance of El Nino conditions emerging over June to August at 95 percent. La Nina, which dominated recent seasons, has just faded, and forecasters expect a rapid flip to the opposite phase. Warm pools of water beneath the surface of the equatorial Pacific have continued to build and spread eastward, the classic fingerprint of an El Nino taking shape.
What has caught the attention of meteorologists is not just that an El Nino is coming, but how big it might become. In its forecast update, Earth Sciences New Zealand said there is a greater than 60 percent probability the event will be classified as strong by spring, with the potential to intensify further as the year goes on. The current pattern of ocean warming closely tracks the early stages of the major El Nino events of 1997 and 1982, two of the most powerful on record. Peak conditions are expected during the summer of 2026 and 2027.
The World Meteorological Organisation has reached a similar view, putting the odds of El Nino developing through the middle of this year at around 80 percent and the chance it lasts into at least November above 90 percent. Forecasters internationally are watching for knock-on effects far beyond the Pacific, including disruption to the Indian monsoon and shifts in the North Pacific storm track.
It helps to be clear about what El Nino actually is. It is one half of a natural seesaw in the Pacific Ocean and atmosphere known as the El Nino Southern Oscillation. During an El Nino the trade winds that normally drag warm water towards Asia weaken or reverse, allowing warmth to pile up across the central and eastern Pacific. That redistribution of ocean heat nudges weather systems around the globe. It is a recurring natural cycle that has operated for thousands of years, distinct from long-term human-driven warming, although it now plays out against a warmer background ocean than in the twentieth century.
For New Zealand, El Nino winters and springs tend to bring more frequent winds from the south and west. That pattern usually means wetter, cooler conditions for the western and southern South Island, while the east of both islands and the upper North Island turn drier than normal. The 1997 and 1998 event brought serious drought to eastern districts the following summer, a reminder that the effects can stretch well past winter into the growing season.
The regional detail in the new outlook follows that script closely. Rainfall is picked to be below normal for Northland, Auckland, Waikato and the Bay of Plenty, and below normal again for Gisborne, Hawke’s Bay and the Wairarapa, with a 50 percent chance of drier than usual conditions in both areas. Coastal Canterbury and eastern Otago are also leaning dry. The West Coast, the Southern Alps, inland Otago and Southland are the parts of the country most likely to see above normal rain, along with cooler temperatures.
Temperatures elsewhere are expected to sit near average for the season overall, which means an El Nino does not guarantee a bitterly cold winter across the board. Forecasters do warn of occasional cold snaps lasting a few days, with the longest and sharpest cold spells most likely inland in the South Island. One colder than average month within an otherwise unremarkable season is a realistic possibility.
Meteorologist Jon Tunster, writing for the forecaster, struck a note of confidence tempered with caution about exactly how the event will land. “Given the projected strength of this event, it will be very surprising if New Zealand doesn’t feel some impacts,” he said, while adding that “surprises are always possible.” Weather, as he put it, remains a mixture of pattern and chaos, and even a strong El Nino only loads the dice rather than dictating every front and dry spell.
The practical stakes are considerable. A drier outlook for the eastern North Island and Canterbury raises early questions about soil moisture and water storage heading towards summer, matters that farmers, growers and councils will be watching closely. A wetter West Coast and Southland brings its own flood and slip considerations. For the rest of the country, the message from forecasters is to treat the season as one where dry stretches in the north and east are more likely than usual, and to plan accordingly.
For now the event is still building, and the forecaster stresses that the strength and timing will become clearer through winter and into spring. The basic mechanics of El Nino are well understood, but every event carries its own character, and this one is shaping up to be a heavyweight worth keeping an eye on.
What is the season doing where you are, and are you noticing the dry creeping into the north and east already? Share your observations 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 🙂
Leave a Reply