Average sea surface temperatures (SST) in the New Zealand region were 0.9 °C below normal in January. The 3–month (November to January) mean departure from normal of -0.6°C is the largest negative seasonal anomaly in at least the last 10 years. SST are expected to continue to be below normal over the next three months.
El Niño weakening
Difference from average global SST (click to enlarge).
Monthly SOI values (click to enlarge).
The current moderate El Niño episode has peaked in the tropical Pacific and is now weakening, but could still influence New Zealand’s climate over the coming season. Most models of the evolution of ENSO suggest that neutral conditions are likely by the end of autumn.
Outlook for February to April 2007
Regional outlook (click to enlarge).
Atmospheric circulation patterns for February to April are likely to feature higher than average pressures to the north of the North Island, with stronger than average westerly airflow over the southern half of the country. Temperatures are expected to be average or below average in the lower South Island, and average elsewhere.
Rainfall is expected to be normal or below normal in the north and east of the North Island, and normal in other regions. Soil moisture and riverflows are expected to be normal in all regions except in the north and east of the North Island, where soil moisture is likely to be normal or below normal and riverflows below normal.