Super El Niño poses extreme weather risk for New Zealand as climate patterns shift

The United Nations Secretary General António Guterres issued a stark warning this week: the world is sliding into a "danger zone of extreme weather," a pronouncement that arrives as three hurricanes spin simultaneously across ocean basins and a strengthening El Niño begins to reshape atmospheric patterns across the Pacific.

El Niño is not a storm or a single event. It is a shift in how the ocean and atmosphere communicate. Normally, trade winds blow steadily from South America toward Papua New Guinea and Australia, pushing warm water westward and allowing cooler water to rise along the South American coast. But when El Niño takes hold, those winds weaken or reverse entirely. The warm water that has accumulated in the western Pacific begins its slow migration back toward the Americas, and the entire global climate system responds. The phenomenon has a name rooted in observation: Peruvian fishermen in the 1600s noticed that around December, warmer currents would arrive and drive the anchovies away. They called it El Niño de Navidad—the Christmas Child—a name that stuck, though the pattern extends far beyond any single season.

Chris Brandolino, chief scientist at Earth Sciences New Zealand, describes El Niño as a mechanism for redistributing heat across the globe. When a strong El Niño develops, the effect is not gradual. "It's like a staircase," Brandolino explained. "Temperatures have been going up, but instead of taking one step at a time, you're taking those long strides and you're taking two steps at a time." A warmer atmosphere holds more water vapor—fuel for intense rainfall. But that same warmth also increases evaporation, which means regions under high pressure systems experience the opposite: settled weather and drought. For New Zealand, the pattern has been consistent enough to predict in broad strokes: the eastern and northern areas of both islands typically dry out while the western regions and lower South Island become wetter than average. Flooding and wildfire risk both increase, though in different places.

Yet Brandolino offered an important caveat. "Every El Niño is different," he said. "We like to tell people we know the average outcome of El Niño, but no El Niño is average." The 2015-2016 event illustrated this unpredictability. Spring was dry as expected, but then moist northeasterly winds arrived in January and February, bringing substantial rain to the upper North Island—the opposite of what the typical El Niño pattern would suggest. History provides a template, not a guarantee.

What concerns scientists now is not just the current El Niño but the rhythm of these events themselves. Historically, El Niño has occurred every two to seven years, a natural oscillation in the climate system. But emerging research suggests climate change is altering that frequency. Since 2020, New Zealand has spent very little time in neutral conditions. Three consecutive La Niña years culminated in 2023 with Cyclone Gabrielle and the Auckland Anniversary floods. A brief neutral period followed, then El Niño arrived, then La Niña returned last year, and now El Niño is establishing itself again. The oscillations are quickening, the swings more pronounced. Brandolino used the word "emerging" carefully when discussing this research—the evidence is still being gathered, the patterns still being understood. But the data points in a direction that demands attention: the climate system that shaped New Zealand's weather for centuries may be entering a new rhythm, one driven not just by natural cycles but by the warming atmosphere humans have created.