Global setting: January 2019

Sea Surface Temperatures (SSTs) remained above average in the equatorial Pacific Ocean during January 2019, particularly near and west of the International Dateline, although declined slightly below the conventional threshold for El Niño.

The probability for oceanic El Niño conditions, according to the consensus from international models, is 74% over February – April period. Compared to last month, the probabilities decreased for autumn 2019 (now 66%, down from 85%) and winter 2019 (now 48%, down from 62%).

However, later in 2019, long-range models indicate the potential re-emergence of oceanic El Niño conditions, which suggests the potential for a ‘protracted’ event. This means that above average SSTs may persist for more than a year across the equatorial Pacific.

Sea Surface Temperatures

New Zealand’s coastal waters for January 2019 remained much warmer than average, with marine heatwave conditions likely being reached in the east of the North Island. SSTs in the Tasman Sea were also well above average, particularly in the central and west, with anomalies of +2.0 to 3.0˚C at month’s end. For the month as a whole, the anomalies do not exceed those observed during the marine heatwave of summer 2017-18.

The forecast models are consistent in predicting above to well above average regional ocean temperatures over the next three-month period (February – April 2019). In the absence of a coupled ENSO event, these regional SSTs are likely to be a dominant driver of New Zealand’s climate over the next three month period.

Differences from average January surface temperatures in the seas around New Zealand
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: Janaury SOI 0.03; November-January average 0.2.