Earth Sciences New Zealand reports that the tropical Pacific Ocean and atmosphere remain firmly in an El Niño state, with atmospheric indicators recording their strongest July values on record. Scientists indicate there is a 90% chance the climate pattern will reach or surpass a very strong intensity, potentially ranking among the strongest events in recent history and bringing significant weather impacts across the country.
Pacific Climate Pattern Reaches Record July Levels
The naturally occurring climate phenomenon originates with the warming of ocean temperatures in the eastern and central equatorial Pacific. According to Earth Sciences New Zealand (ESNZ), the tropical Pacific Ocean and atmosphere have stayed firmly in an El Niño state, while atmospheric indicators registered their strongest July values on record. ESNZ noted that the event remains in its early stages, meaning impacts on weather patterns are yet to be fully felt but are anticipated during the current outlook period.
Forecast Rainfall Shifts and Regional Impacts
As the climate pattern builds, weather patterns are expected to shift towards persistent westerly winds over the next three months. ESNZ stated that rainfall will likely sit below normal across much of the North Island, alongside eastern regions of both islands. By contrast, the West Coast and lower South Island are forecast to receive above-normal rainfall, raising the risk of heavy rain and strong wind events as spring progresses. The agency pointed out that northerly rain events, which brought heavy rain from the north over the past year, have already dropped in frequency in recent months. That trend is expected to continue, shifting the main heavy rain threat toward the western and lower South Island.
Temperatures, Water Supplies, and Wider Influences
Temperatures from August to October are expected to hover near or above average across most of the country, though ESNZ cautioned that this does not guarantee consistently warm weather. Cold snaps remain likely through winter and spring, while stronger westerly winds will bring greater swings between warm and cool conditions. The drier outlook is projected to impact water supplies as well. ESNZ forecast that soil moisture levels and river flows will sit near or below normal across much of the north and east of both islands, as well as parts of the western North Island and northern South Island. Reduced rainfall in several regions is likely to limit groundwater recharge, creating challenges for water-dependent sectors.
Historical Context and Future Scenarios
Scientists estimate there is about a 90% chance the event will reach or surpass a very strong intensity during the outlook period. Peak conditions and potential significant impacts are expected during the 2026-27 summer. If that occurs, ESNZ said the event would likely rank among the strongest El Niño events in recent history. Historical precedent shows the top five strongest El Niño events occurred in 1972, 1982, 1991, 1997, and 2015, all of which featured sea surface temperature anomalies near or slightly above 2.5C. While other climate drivers—including the Indian Ocean Dipole, Southern Annular Mode, and Madden-Julian Oscillation—will continue to influence conditions, ESNZ expects El Niño to become the dominant driver over the coming months. The agency is also monitoring the possibility of a rare Southern Hemisphere sudden stratospheric warming event, which could further influence New Zealand’s weather if it occurs.
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