Retrospective - August to October Outlook

For August–October 2013, higher pressures than normal were forecast south of New Zealand, while lower pressures than normal were expected to the north over Australia and the Coral Sea.

This circulation pattern was expected to produce a weaker than normal westerly flow over the country. Lower MSLP’s than normal dominated the New Zealand region during the forecast period. Particularly negative pressures were observed south of Australia extending eastwards into the south Tasman Sea. This climate pattern resulted more westerly airflows than usual across New Zealand. Note that the ENSO-neutral conditions were expected to persist over the August–October period. This forecast was well advised with neutral conditions persisting over the equatorial Pacific Ocean.

Predicted rainfall:  Rainfall is forecast to be normal or above normal in the east and north of the North Island as well as the west of the South island, while normal or below normal rainfall is likely for the west of the North Island and the north of the South Island. Normal rainfall is expected for the east of the South Island.

Outcome: Actual rainfall for the forecast period was above normal for the west of the South Island, with closer to normal rainfalls observed for all other regions of the country. In spite this, isolated areas of above normal rainfall were recorded across Stewart Island, Invercargill, Kaikoura, north-eastern Tasman, Kapiti Coast, Horowhenua, western Masterton, western Carterton, Taranaki, Hastings and coastal Gisborne Districts. 

Predicted air temperature: Temperatures are very likely to be above average in the North Island regions as well as in the north of the South Island, and likely to be average or above average in the east and west of the South Island. Nevertheless, cold snaps, frost and snow conditions will of course still occur in many areas from time to time, as is typical of this time of year.

Outcome: The forecast was well advised with above average temperatures between 0.5-2.0°C observed across all regions. However, pockets of closer to normal conditions were recorded in parts of the Far North, southern Hawkes Bay, Grey and central Otago.