As a result, central Pacific Ocean surface temperatures are now at their warmest level since the El Niño of 1997-98, exceeding temperatures observed in both the 2002-03 and 2006-07 events. During the past week, small regions which are more than 3°C above their average temperature have emerged along the equator.

Leading climate models continue to suggest tropical ocean temperatures are approaching their peak, and will remain above El Niño thresholds through the southern summer before starting to cool.

Over the past fortnight, the Southern Oscillation Index has fallen slightly, and remains at levels typical of an El Niño event. Similarly, cloudiness and rainfall near the equator remains enhanced, while eastern Austrailan rainfall remains low; all typical of a mature El Niño event. However, the influence of El Niño events on Australian rainfall typically declines by mid to late summer.

The Indian Ocean Dipole (IOD) has a reduced impact upon Australia over the summer months.

In Brief

• The tropical Pacific Ocean sea surface remains significantly warmer than the long-term average in central and eastern areas.
• The sub-surface water of the tropical Pacific remains warmer than the long-term average.
• The latest approximate 30-day SOI value is −10; the monthly value for November was −7. The SOI has remained relatively stable throughout December.
• Trade winds are weaker than normal across the Pacific.
• Cloudiness near the date-line has increased over the past fortnight.
• All of the above are consistent with a moderately strong El Niño, which most leading international computer models surveyed by the Bureau predict will persist through the southern hemisphere summer, but decline thereafter.