Retrospective - August to October Outlook

The climate we predicted and what actually happened. 

The tropical Pacific was expected to remain in the neutral range (neither La Niña nor El Niño) during the August-October period, but by October, weak La Niña conditions had re-developed. Mean sea level pressures were expected to be above normal to the south and southeast of New Zealand, with weaker westerlies over the country, for the season as a whole. In actual fact, higher pressures than usual prevailed over the south Tasman Sea and over New Zealand during the season, producing more southerly airflows over the country. The anomalous southerly flows produced a generally dry and sunny season over the country, with the exception of the eastern South Island (which was wetter than normal). However, the southerly regime meant it was cooler than forecast. 

Predicted rainfall: Seasonal rainfall is likely to be near normal in all regions of the country, except for the east of the South Island where normal or below rainfall and soil moisture is likely.

Outcome: The anomalous southerly flows resulted in below average seasonal rainfall across the northern and western regions of both Islands, as well as in Gisborne and parts of Hawkes Bay. Near normal rainfall was recorded for Taranaki, Manawatu, south Hawkes Bay, the Wairarapa, Nelson, Marlborough, Kaikoura Coast, and much of Canterbury, Otago and eastern Southland, although there were small pockets along the south Canterbury coast, inland Otago and around Invercargill which experienced above normal rainfall.

Predicted air temperature: Air temperatures are likely to be near average or above average in all regions, except for the east of the South Island where near average temperatures are likely. Cold snaps typical of winter will occur from time to time through the period.

Outcome: Temperatures were below average for most of the country, with near normal temperatures observed in parts of Northland, Auckland, the Bay of Plenty, Taranaki, Ruapehu, Marlborough, north Canterbury, the majority of the Lakes District, around Westport, and coastal Southland.