The sea surface around New Zealand was on average 0.1°C cooler than normal in February, although surface temperatures have risen considerably since December 2006. The 3–month (Dec–Feb) temperature anomaly was –0.4°C.
El Niño weakening
Difference from average global SST (click to enlarge).
Monthly SOI values (click to enlarge).
The moderate El Niño event in the tropical Pacific weakened rapidly during January and February and oceanic conditions are now in a neutral state. For the coming season, the majority of ENSO (El Niño Southern Oscillation) models suggest that ENSO-neutral conditions will continue with a 30% chance of a La Niña event (also see). Sea surface temperatures are now variable across the equatorial Pacific, about +0.4 °C above average in places from the Date Line to South America, with some areas now slightly below average. Conditions in the tropical Pacific are therefore not expected to affect New Zealand’s climate during autumn.
Outlook for March to May 2007
Regional outlook (click to enlarge).
Atmospheric circulation patterns for March to May are likely to feature higher than average pressures over and to the east of New Zealand, and an anomalous north or northeast airflow over the eastern Tasman and New Zealand.
Temperatures are expected to be average or above average over the country. Rainfall is expected to be normal in most districts, but above normal over northern New Zealand. Normal or above normal soil moisture and stream flows are likely in the north of the North Island. Elsewhere, normal soil moisture and stream flows are likely.