Global Setting – May 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 (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. 

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 5th of May to 1st of June 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: May SOI +0.8; March to May average +0.6.