Weather

The NINO3.4 Index anomaly (in the central Pacific) during November (through the 28th) was -0.59˚C and the Southern Oscillation Index (SOI) was +1.1, both near the La Niña threshold. The three month average SOI was +0.9.

Summer temperatures are very likely to be above average across the country. Warm overnight temperatures and extended periods of high humidity are likely.

The NINO3.4 Index anomaly (in the central Pacific) during October was -0.59˚C. The latest weekly value was -0.80˚C, continuing the trend towards La Niña. The Southern Oscillation Index (SOI) was +0.7 during October and August-October, on the La Niña side of neutral. Overall, this represented an ocean-atmosphere system that was on the verge of La Niña conditions.

5th-warmest October on record

The NIWA and MetService assessment of named tropical cyclone (TC) activity indicates 9 to 12 named TCs could occur in the Southwest Pacific basin between November 2021 and April 2022. The seasonal outlook is for normal to slightly above normal activity in terms of overall named TCs in the region

The NINO3.4 Index anomaly (in the central Pacific) during September was -0.23˚C. Compared to this time last year, conditions are about 0.5˚C warmer. The Southern Oscillation Index (SOI) was +0.8 during September, on the La Niña side of neutral. Notably, the three-month average SOI was +1.0, in La Niña territory.

The NINO3.4 Index anomaly (in the central Pacific) during August was -0.17 ̊C. The Southern Oscillation Index was +0.5. While both remained in neutral territory, other indicators trended toward La Niña.

New Zealand’s second consecutive warmest winter on record

A warm finish to winter for most of the country

Spring rainfall is most likely to be below normal in the east of the North Island, near normal in the west of the South Island, and about equally likely to be near normal or below normal in all remaining regions across Aotearoa New Zealand.