Retrospective - December to February Outlook

In the New Zealand region for December 2013–February 2014, lower pressures than normal were forecast to the north of the country in the western Pacific, while anticyclonic conditions were forecast over the south and to the east of the country.

This circulation pattern was expected to be associated with slightly less westerly and southwesterly airflow than usual over the summer.

Overall, pressures were below normal across the New Zealand region during the forecast period, with higher pressures than normal well to the south-east of the country. This circulation pattern led to a south-west flow anomaly overall over New Zealand.  

Predicted rainfall: Rainfall totals over the December–February period as a whole are most likely (45% chance) to be near normal in all regions except for the north of the North Island, where rainfall is equally likely (40% chance) to be near normal or above normal. 

Outcome: Actual rainfall for the forecast period was highly variable across New Zealand with below normal rainfall observed across much of the North Island and pockets of the South Island. Particularly drier than normal conditions (<40% of normal rainfall) were observed in the Waitomo, Matamata-Piako, South Waikato, Taupo and Ruapehu Districts as well as the South Wairarapa and Waimate Districts. In contrast, pockets of above normal rainfall (>120% normal) were recorded across the coastal fringes of north-eastern Northland, Kaikoura, Dunedin City and south-western Southland. 

Predicted temperature: Temperatures over the December–February period as a whole are equally likely (40% chance) to be near average or above average in the north and east of the North Island and the east of the South Island, while above average temperatures are the most likely outcome (45 to 50 % chance) for the remaining regions of the New Zealand. 

Outcome: This temperature forecast was well advised for north and east of the North Island as well as the east of the South Island; however, temperatures were closer to normal for remaining areas of New Zealand with much cooler than normal expected temperatures (between -0.5°C and -1.0°C below normal) recorded in parts of the Waitomo, Otorohanga, Waipa and Clutha Districts.