Global setting and climate outlook

Global setting and climate outlook

La Niña indicators strengthen

Difference from average global SST (click to enlarge).

Monthly SOI values (click to enlarge).

Conditions in the tropical Pacific are in a borderline La Niña state, with some strengthening of this phase of the El Niño-Southern Oscillation over the past month. There is a 60% chance of La Niña conditions developing in the equatorial Pacific during the spring (September–November) forecast period, with less than a 10% chance of El Niño conditions developing. However the Southern Oscillation Index remains near zero.

Sea surface temperatures(SST) around New Zealand

New Zealand SST (click to enlarge).

Sea surface temperature (SST) anomalies in the New Zealand region continued to weaken in August to +0.4 °C, with the June–August average anomaly about +0.6 °C. SST anomalies are positive around the North Island east coast and across to the central Pacific, but remain negative south of Chatham Rise and southeast of the South Island. SSTs are expected to remain above normal around the North Island, but are likely to be near normal around the South Island.

Outlook for September to November 2007

Regional outlook (click to enlarge).

During spring, mean sea level pressures are expected to be higher to the southwest of New Zealand and lower than normal to the north, with weaker than normal westerly winds (more easterly anomalies) across the country. Air temperatures are likely to be average or above average in all regions.

Above normal rainfall is expected in the east of the North Island, with normal or below normal rainfalls likely elsewhere. Soil moisture levels and stream flows are likely to be normal or below normal in the South Island and west of the North Island. Normal or above normal conditions are likely in the east of the North Island, and normal conditions are likely in the north of the North Island.