Retrospective - September to November Outlook

A weak, short-lived El Niño was predicted for spring, since borderline El Niño conditions were evident at the end of winter. However, while the global ocean reached El Niño thresholds, the atmosphere failed to couple up, and the atmospheric system remained within neutral territory.

Over the spring period (September-November), higher than normal pressures were expected in the south Tasman and over southern New Zealand, along with lower pressures to the north of the North Island, resulting in weaker than normal westerlies over the country. However, a pattern similar to the characteristic El Niño response was instead observed, with enhanced southwest winds over New Zealand during spring.

Predicted rainfall: Rainfall totals are likely to be above normal or near normal in the north and east of the North Island, and near normal in the southwest of the North Island and in Nelson-Marlborough. In the west, south and east of the South Island, rainfall totals are likely to be near normal or below normal.

Outcome: Below normal spring rainfall was observed across much of the North Island, Nelson and Marlborough, with near normal spring rainfall recorded in parts of Northland, the Gisborne Region, the Tasman Region, Buller, much of central and north Canterbury, parts of Otago and western Southland. In contrast, it was generally wetter than forecast across the remainder of the southeast, south, and western South Island (with normal to above normal spring rainfall recorded).

Predicted air temperature: Temperatures are likely to be near average in all regions of the country. The occurrence of frosts and spring snowfalls cannot be ruled out.

Outcome: Temperatures were cooler than forecast, mainly due to an unusually cool November. Below average spring temperatures were observed across most regions of New Zealand. The exceptions were eastern Northland, Auckland, western Bay of Plenty, parts of the Gisborne Region, parts of Taranaki, between Palmerston North and the Kapiti Coast, much of the Wairarapa, the Tasman Region, Nelson, Marlborough, North Canterbury, Dunedin, as well as much of Southland; where near average seasonal temperatures were observed.