What happened in October, how our climate outlook for the previous three months turned out, global and local sea temperatures, and our outlook for November to January.
It was a relatively stormy October, with more frequent southwest winds and lower pressures than usual affecting New Zealand. These southwesterly winds produced a rather cool October for the south and west of the South Island, and very dry conditions in the eastern North Island.
Oceanic indicators in the west and central tropical Pacific remain close to El Niño thresholds, but the atmosphere has yet to show any significant response to the warmer than normal sea surface temperatures. The global forecast models indicate an approximately 50:50 chance of neutral versus weak El Niño conditions over the next three months. In the New Zealand region, lower than normal pressures are expected southeast of the Chatham Islands, with weakly enhanced south-westerly winds over New Zealand.
November-January temperatures are likely to be average or above average in the southwest and east of the North Island, and in Nelson-Marlborough, and near average in other regions. Sea surface temperatures are expected to remain near average around New Zealand. Rainfall is likely to be near or below normal in the north of both Islands, but near normal overall in other regions.
Conditions in the tropical Pacific were on the brink of El Niño at the start of this forecast period, and El Niño development was signalled during August-October. Tropical Pacific Ocean temperatures did reach the El Niño threshold, but the atmosphere has yet to show any significant response to the warmer than normal sea surface temperatures. In the New Zealand region, the stronger than normal spring westerlies often associated with El Nino periods were not expected to be very prominent, with higher pressures than usual expected instead south of the country.
