May 2013 was characterised by lower pressures than usual over and to the east of New Zealand, with higher than normal pressures to the southwest of the country. This meant more northwesterly winds than normal affected the North Island, and more southeasterly winds than normal affected the South Island. It was a warmer than usual month for much of the North Island, due to this air flow. Very cold southerly air flow resulted in widespread snowfall over Southland, Otago, and parts of Canterbury, as well as the Central Plateau, as well as low temperatures and high winds to the North Island, on 27-29 May.
New Zealand Climate Update 168 – June 2013
What happened in May, how our climate outlook for the previous three months turned out, global and local sea temperatures, and our outlook for June to August.
The equatorial Pacific Ocean remains in a neutral state (neither El Niño nor La Niña). International guidance indicates that these neutral conditions are likely to persist over the coming three months (June–August). In the New Zealand region higher than normal pressures are forecast south and southeast of the country, whereas lower than normal pressures are expected to the west and north of New Zealand. This circulation pattern is expected to be associated with more northerly and north-easterly airflow than usual.
Rainfall for the June–August period as a whole is likely to be in the normal or above normal ranges in the north and east of the North Island, and near normal for the southwest of the North Island and for all the South Island.
Winter (June–August) temperatures are very likely to be above average across the entire country. However, occurrences of frost and snow conditions should of course still be expected in many areas.
Predicted rainfall: Rainfall is likely to be in the near normal range for all regions.
Outcome: Rainfall was below normal for the west and south of the South Island, the central North Island, Hawkes Bay, Gisborne and parts of Northland. It was wetter than normal for much of the Auckland Region as well as, northern parts of the Waikato Region, the top of the South Island and coastal areas of both Canterbury and Otago. Normal rainfall few elsewhere.