Seasonal Climate Outlook

Seasonal Climate Outlook December 2024 - February 2025

A La Niña Watch remains in effect, with a little over 50% chance that La Niña officially develops by the end of the year.

A La Niña Watch remains in effect with a 60-70% chance that an event officially develops by December.

Seasonal Climate Outlook for September - November 2024

La Niña-like atmospheric patterns continued during July and a La Niña Watch continues. Oceanic La Niña may develop during spring (60% chance)

Following La Niña-like atmospheric patterns near New Zealand during June, a La Niña Watch continues. There’s a 60-70% chance that La Niña will develop during spring.

El Niño, which was active since September 2023, has ended and given way to ENSO neutral conditions, which are expected to last through winter.

El Niño is expected to ease to ENSO neutral by the end of May.

El Niño is expected to ease to ENSO neutral by June.

El Niño is expected to ease to ENSO neutral by the end of autumn. The autumn season is favoured to have more northwesterly winds than normal around Aotearoa/New Zealand.

El Niño continued during January and has around a 100% chance of persisting through April.

El Niño continued during December and has around a 100% chance of persisting through to March 2024.

El Niño continued during November and has around a 100% chance of persisting through summer and an 85% chance of persisting through autumn. Although it will have an important influence on Aotearoa New Zealand’s climate, unusual ocean heat in the western equatorial Pacific and on a global scale has contributed to circulation patterns that are not typically associated with a traditional El Niño.

El Niño continued during October and will likely intensify over the next three months. It has around a 100% chance of persisting during this time. There’s an 80% chance of El Niño continuing through autumn, maintaining an important influence on Aotearoa New Zealand’s climate.

El Niño has officially arrived. A majority of NIWA’s criteria for classifying an El Niño event were satisfied during September. In particular, the Southern Oscillation Index was firmly in El Niño territory, suggesting the atmosphere has become coupled to the ocean.

El Niño Alert criteria continued to be met during July. Central equatorial Pacific sea surface temperatures (SSTs) exceeded El Niño thresholds but the Southern Oscillation Index (an atmospheric indicator) was neutral. Full ocean-atmosphere coupling for El Niño is expected in the next three months, likely persisting through summer.

El Niño Alert criteria was reached during June. Central equatorial Pacific sea surface temperatures (SSTs) exceeded El Niño thresholds, but the Southern Oscillation Index (an atmospheric indicator) was neutral. The ocean-atmosphere system is expected to progress toward El Niño conditions from late winter into spring.

ENSO-neutral conditions persisted during May, but oceanic and atmospheric indicators trended closer to El Niño thresholds. El Niño will continue to develop during winter with the potential for a strong event developing by spring.

ENSO-neutral conditions persisted in April however seas continue to warm across the equatorial Pacific consistent with a developing El Niño. El Niño conditions may arrive during winter.

La Niña ended during March, concluding its three-year run. A dramatic change in tropical trade winds resulted in warming seas across the equatorial Pacific. As of late March, ENSO-neutral conditions were occurring, but El Niño conditions may arrive as early as winter. An El Niño Watch has been issued to cover this potential.

La Niña is expected to transition to ENSO-neutral during March. For Aotearoa New Zealand, this transition is expected to result in more variable air flow, temperature, and rainfall patterns during autumn.

La Niña continued during January, but it has gradually weakened. It will continue to affect Aotearoa New Zealand’s atmospheric patterns in coming months, even as neutral conditions are likely reached in early autumn.

La Niña continued during December and a marine heatwave intensified in Aotearoa New Zealand’s coastal waters with sea surface temperatures (SSTs) 1.1˚C to 1.8˚C above average. La Niña is most likely to ease to neutral by early autumn.

Summer temperatures are about equally likely to be near average or above average in the east of both islands, very likely to be above average in the north of the North Island and the west of both islands, and most likely to be above average in the north of the South Island