Retrospective: December-February 2017 Outlook

The combination of easing La Nina conditions, along with the absence of other large-scale climate drivers resulted in no clear air flow anomaly forecast for December-February. Typical summer conditions were expected with anticyclones crossing the North Island and prevailing westerly winds over the South Island. Actual pressures were lower than normal over New Zealand and particularly low to the southwest of the country. This pressure setup led to more westerly and south-westerly winds than normal during the summer season. 

Predicted air temperature: December 2016 - February 2017 temperatures were most likely to be near average for the west of the North Island and about equally likely to be near average or above average for the remainder of the country.

Outcome: Actual seasonal temperatures were mostly near average in the North Island with the exception of parts the Wellington, Taranaki and Waikato regions where below average temperatures were recorded. In the South Island, temperatures were mostly below average. The exceptions were Marlborough and eastern parts of the Canterbury and Otago regions where temperatures were near average.

Predicted rainfall: December 2016 - February 2017 rainfall totals about equally likely to be near normal or below normal for the east of the South Island and mostly likely to be near normal for the rest of New Zealand.

Outcome: Actual rainfall was below normal for much of the north of the North Island as well as Gisborne and northern parts of Hawke’s Bay. The remainder of the North Island saw near normal rainfall. In the South Island rainfall was largely near normal. The exceptions were the western fringes of Tasman, the West Coast and Southland. Small pockets of below normal rainfall were found in the Hurunui and Mackenzie districts.