Global Setting – April 2013

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 (May–July). In the New Zealand region higher pressures than normal are forecast south of the country extending towards the east of the Chathams Islands, while lower pressures than normal are expected to the north of New Zealand. This circulation pattern is expected to be associated with weaker than normal westerly flow. 

Sea Surface Temperature

Sea surface temperatures around New Zealand's coasts are also forecast to be above the climatological average for the coming three months. 

Differences from average global sea surface temperatures for 31st of March to 27th of April 2013. Map courtesy of NOAA Climate Diagnostics Centre (http://www.cdc.noaa.gov/map/images/sst/sst.anom.month.gif).
Monthly values of the Southern Oscillation Index (SOI), a measure of changes in atmospheric pressures across the Pacific, and the 3-month mean (black line). SOI mean values: Apr SOI 0.0; February to April average +0.2.
Differences from normal April surface temperatures in the seas around New Zealand.