Given its current strength and the typical life cycle of El Niño events, this event is expected to persist into the autumn of 2027 (March), said the report. | Photo Credit: NAGARA GOPAL

El Nino continues to strengthen, with temperatures in the Pacific Ocean now well above normal. The latest Niño 3.4 index has increased to 2.51°C, and it is forecast to intensify over the coming months.

Meanwhile, the Indian Ocean Dipole (IOD) has returned above the positive threshold. While a positive IOD has not yet been confirmed, models suggest one may develop this spring, according to the Southern Hemisphere Monitoring report by the Bureau of Meteorology, Australia.

Historic warming

All models, including the bureau’s, predict further warming of the tropical Pacific for the southern hemisphere spring (September-November), likely peaking in late spring or summer (December-February).

Relative Niño 3.4 values are predicted to surpass the warmest values observed since reliable records began in 1950, with most models forecasting a peak value above +3.0 °C.

Given its current strength and the typical life cycle of El Niño events, this event is expected to persist into the autumn of 2027 (March), said the report.

The Southern Oscillation Index (SOI), an indicator of the atmospheric component of the El Niño–Southern Oscillation (ENSO), remains strongly negative, with the latest 30-day SOI to 13 September 2026 at -18.5, well below the El Niño threshold of -7.

The atmosphere also shows a strong El Niño, with weakened or reversed trade winds in the western to central tropical Pacific, increased cloudiness across the central to eastern tropical Pacific and reduced cloudiness over the Maritime Continent.

IOD Strengthens

The Indian Ocean Dipole (IOD) is currently neutral, while the IOD index value for the week ending 13 September 2026 is +0.65 °C. After 4 weeks in the neutral range, the index is once again above the positive IOD threshold (+0.4 °C), but this does not signify that a positive IOD is underway, the report added.

Models indicate a positive IOD is likely to develop in the Southern Hemisphere spring, although there is uncertainty about the strength and duration of the event.

Warmer Seas

The analysis of sea surface temperature (SST) for the week ending 13 September 2026 indicates waters warmer than normal surrounding much of Australia and near-normal temperatures in most areas to the north (with some exceptions along northern coastlines). In particular, the waters around the southern New South Wales and eastern and southern Tasmanian coasts are hot, peaking at around 2 to 3°C above average.

The Global SSTs (60°S to 60°N) for August 2026 in the NOAA ERSSTv5 dataset were the warmest on record, at 1.04 °C above the 1961-1990 average, the report added.

Published on September 15, 2026