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Northland is likely to experience above-average temperatures and below-normal rainfall through to the end of December as a very strong El Niño strengthens across the tropical Pacific.
According to Earth Sciences New Zealand’s latest seasonal outlook, Northland, Auckland, Waikato and the Bay of Plenty have a 50% chance of above-average temperatures and a 45% chance of below-normal rainfall between October and December 2026.
Soil moisture levels and river flows are about equally likely to be below normal, at 45%, or near normal, at 40%.
Earth Sciences New Zealand says very strong El Niño conditions are now present in the tropical Pacific and are expected to strengthen further.
It says El Niño’s influence on New Zealand’s weather patterns is becoming increasingly apparent and is expected to be a dominant driver of climate patterns during the outlook period.
More frequent westerly airflows are also expected across New Zealand, accompanied by stronger and gustier winds. This is likely to produce more frequent fronts in western and southern areas while increasing the potential for dry, warm föhn conditions in eastern regions.
According to the outlook, temperatures are expected to be above average across most of New Zealand between October and December 2026. Despite the generally warmer outlook, greater variability is expected, with marked shifts between warm and cold conditions.
Rainfall totals for October–December 2026 are most likely to be below normal in the north and east of the North Island.
El Niño is forecast to peak in late spring or early summer and could rank among the strongest events on record. Earth Sciences New Zealand says the Relative Oceanic Niño Index has already surpassed levels recorded at the same point in 1997, following the fastest warming observed to date.
