An El Niño event has been officially declared as present in the tropical Pacific.
The declaration marks the onset of a climate pattern characterised by warmer-than-average sea surface temperatures across the central and eastern equatorial Pacific Ocean. This oceanic phenomenon typically develops every 2 to 7 years and can persist for several months, influencing weather systems across vast regions of the globe.
Scientists have warned the event could become the most intense ever recorded. The assessment reflects monitoring data and modelling projections that track sea surface temperature anomalies and atmospheric coupling patterns across the Pacific basin.
Previous strong El Niño events have been associated with significant disruptions to global weather patterns, including altered rainfall distributions, temperature extremes, and changes to seasonal conditions across multiple continents. The strength of an El Niño event is typically measured by the magnitude and persistence of temperature departures from long-term averages in key Pacific monitoring regions.
The El Niño event is expected to affect New Zealand's spring weather patterns. During El Niño conditions, the country typically experiences shifts in prevailing wind patterns and moisture transport mechanisms that can influence temperature, precipitation and storm track positioning during the September to November period.
El Niño events interact with New Zealand's climate through their influence on atmospheric circulation patterns across the southwest Pacific. These circulation changes can modify the frequency and intensity of weather systems approaching the country from different directions, though the specific impacts vary depending on the event's strength, timing and spatial characteristics.
The official declaration follows months of monitoring by climate agencies that track ocean and atmosphere indicators across the tropical Pacific. Such declarations are based on sustained observations meeting defined threshold criteria for sea surface temperatures, atmospheric pressure patterns and wind conditions across the region.