Summary for New Zealand

A transition to ENSO-neutral is likely during late Southern Hemisphere spring or early winter 2016, with a possible transition to La Niña conditions during the spring. Indicative of a strong El Niño, sea surface temperature (SSTs) anomalies were in excess of 2°C across the east-central equatorial Pacific Ocean during January. The Niño indices in the eastern Pacific declined, while Niño-3.4 and Niño-4 were nearly unchanged. The subsurface temperatures in the central and eastern Pacific increased due to a downwelling Kelvin wave, but toward the end of the month weakened again in association with the eastward shift of below-average temperatures at depth in the central Pacific. Also, low-level westerly wind anomalies and upper-level easterly wind anomalies continued over much of the tropical Pacific. The traditional and equatorial Southern Oscillation Index (SOI) values remained negative but weakened relative to last month. Convection remained much enhanced over the central and east-central tropical Pacific and suppressed over Indonesia. Collectively, these anomalies reflect the continuation of a strong El Niño. Most models indicate that El Niño will weaken, with a transition to ENSO-neutral during the late autumn or early winter 2016. Thereafter, the chance of La Niña conditions increases into the spring. While there is both model and physical support for La Niña following strong El Niño, considerable uncertainty remains. A transition to ENSO-neutral is likely during late Northern Hemisphere autumn or early winter 2016, with a possible transition to La Niña conditions during the spring.

North Island

Temperature

March

Almost all of the North Island should be slightly above normal.

April

Almost all of the North Island should be moderately above normal with the Hawkes Bay being only slightly warmer than normal.

Precipitation

March

Drier than normal through Northland and Auckland and into the North Waikato and from East Cape down toward Wellington. The rest of the island should be near normal.

April

Northland down to the north Waikato should be slightly to moderately wetter than normal with the rest of the island near normal.

South Island

Temperature

March

Almost all of the South Island should be slightly to moderately above normal.

April

Almost all of the South Island should be slightly to moderately above normal except near normal in South Canterbury.

Precipitation

March

Most of the island should be near normal to slightly to moderately wetter than normal in the north and east.

April

Near normal to slightly wetter than normal across the eastern half of the island and far north and near normal elsewhere.

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