Summary for New Zealand

NOAA El Niño Advisory: There is a greater than 90% chance that El Niño will continue through Southern Hemisphere summer 2015-16, and around an 85% chance it will last into early fall 2016.

During July, sea surface temperatures (SST) anomalies were near +1.0oC in the central equatorial Pacific Ocean, and in excess of +2.0oC across the eastern Pacific. SST anomalies increased in the Niño-3 and Niño-3.4 regions, while the Niño-4 and Niño-1+2 indices decreased slightly during the month. Positive subsurface temperature anomalies strengthened in the central and east-central equatorial Pacific during the month, in association with the eastward movement of a downwelling oceanic Kelvin wave. The atmosphere remained coupled to the oceanic warming, with significant low-level westerly wind anomalies continuing from the western to east-central equatorial Pacific, along with anomalous upper-level easterly winds. Also, the traditional and equatorial Southern Oscillation Index (SOI) were both negative, consistent with enhanced convection over the central and eastern equatorial Pacific and suppressed convection over Indonesia. Collectively, these atmospheric and oceanic features reflect a significant and strengthening El Niño.

All models surveyed predict El Niño to continue into the Southern Hemisphere autumn 2016, and all multi-model averages predict a strong event at its peak in late spring/early summer (3-month values of the Niño-3.4 index of +1.5oC or greater. At this time, the forecaster consensus unanimously favours a strong El Niño, with peak 3-month SST departures in the Niño 3.4 region potentially near or exceeding +2.0oC. Overall, there is a greater than 90% chance that El Niño will continue through Southern Hemisphere summer 2015-16, and around an 85% chance it will last into early fall 2016.

Northland

Temperature

September

Slightly cooler (0.5 degrees C) over the entire region.

October

Near normal over the entire region.

Precipitation

September

Slightly drier than normal throughout the region.

October

Near normal across the entire region except the far north that should be slightly drier than normal.

Auckland

Temperature

September

Slightly cooler (up to 0.5 degrees C) over the entire region.

October

Slightly cooler (up to 0.5 degree C) over the entire region.

Precipitation

September

Near normal to slightly drier throughout the region with areas of moderate dryness in the south.

October

Near normal throughout the region.

Waikato

Temperature

September

The entire region should be up to 0.5 degrees C cooler than normal.

October

The entire region should be up to 0.5 degrees C cooler than normal.

Precipitation

September

Slightly drier than normal over most of the region except the northernmost part that should be near normal.

October

Slightly drier than normal over most of the region except the northernmost part that should be near normal.

Bay of Plenty

Temperature

September

The entire region should be up to 0.5 degrees C cooler than normal.

October

The entire region should be up to 0.5 degrees C cooler than normal.

Precipitation

September

The entire region should be slightly drier than normal.

October

The entire region should be slightly drier than normal.

Gisborne

Temperature

September

The entire region should be up to 0.5 to 1.0 degrees C cooler than normal.

October

The entire region should be up to 0.5 degrees C cooler than normal.

Precipitation

September

The entire region should be near normal to slightly drier than normal.

October

The entire region should be near normal to slightly drier than normal.

Hawke’s Bay

Temperature

September

Much of the region could be 0.5 degrees C cooler than normal.

October

Much of the region could be 0.5 degrees C cooler than normal.

Precipitation

September

Much of the region should be normal to slightly drier than normal.

October

Much of the region should be normal to slightly drier than normal.

Taranaki

Temperature

September

The entire region should be up to 0.5 degrees C cooler than normal.

October

The entire region should be up to 0.5 degrees C cooler than normal.

Precipitation

September

The entire region should be slightly to moderately drier than normal.

October

The entire region should be slightly drier than normal.

Manawatu-Wanganui

Temperature

September

The entire region should be up to 0.5 degrees C cooler than normal.

October

The entire region should be between 0.5 and 1.0 degrees C cooler than normal.

Precipitation

September

Much of the region should be slightly to moderately drier than normal.

October

Much of the region should be near normal except for the western areas that should be drier than normal.

Wellington

Temperature

September

The entire region could be up to 0.5 degrees C cooler than normal.

October

The entire region could be up to 0.5 to 1.0 degrees C cooler than normal.

Precipitation

September

The entire region should be slightly drier than normal.

October

The entire region should be near normal to slightly drier than normal.

Tasman

Temperature

September

The entire region should be near normal to slightly cooler in the north.

October

The entire region should be slightly cooler than normal except the far south should be slightly warmer than normal.

Precipitation

September

The entire region should be slightly to moderately drier than normal.

October

The entire region should be slightly to moderately drier than normal.

Nelson

Temperature

September

The area should be slightly cooler than normal.

October

The area should be slightly cooler than normal.

Precipitation

September

The area should be moderately drier than normal.

October

The area should be near slightly drier than normal.

Marlborough

Temperature

September

The northern half of region could be up to 0.5 degrees C cooler than normal while the southern half could be up to 1.0 C warmer than normal.

October

The northern half of region could be up to 1.0 degrees C cooler than normal while the southern half could be up to 1.0 C warmer than normal.

Precipitation

September

Nearly the entire region should be slightly to moderately drier than normal.

October

Nearly the entire region should be slightly to moderately drier than normal.

West Coast

Temperature

September

The most southern part of the region should be near normal to slightly cooler than normal and the coastal part of the rest of the region should be near normal while the alpine regions could be up to 2.0 degrees C warmer than normal.

October

Nearly the entire region could be up to 0.5 degrees C cooler than normal except the far north and alpine areas which could be slightly to moderately warmer than normal.

Precipitation

September

The entire region should be slightly drier than normal.

October

The entire region should be slightly drier than normal.

Canterbury

Temperature

September

Much of the eastern half of the region should be slightly to moderately cooler than normal and slightly to moderately warmer than normal in the alpine areas.

October

Much of the eastern half of the region should be slightly cooler than normal and slightly to moderately warmer than normal in the alpine areas.

Precipitation

September

The entire region should be near normal in the east and slightly to moderately drier than normal elsewhere.

October

The region should be near normal in the plains and slightly drier in the Alps.

Otago

Temperature

September

Much of the region should be near normal to slightly cooler than normal.

October

Much of the region should be near normal to slightly cooler than normal.

Precipitation

September

Much of the region should be slightly drier than normal and the southeast of the region near normal.

October

Much of the western half of the region should be slightly to moderately drier than normal and the eastern half of the region near normal.

Southland

Temperature

September

Much of the region should be normal to slightly cooler than normal except for Fiordland that could be moderately cooler than normal.

October

Much of the region should be normal except for Fiordland that could be moderately cooler than normal.

Precipitation

September

Most of the western half of the region should be slightly drier than normal and the remainder near normal.

October

Much of the eastern half of the region should be near normal.

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