La Niña is an oceanic and atmospheric phenomenon that is the colder counterpart of El Niño, as part of the broader El Niño–Southern Oscillation climate pattern.

The bureau is reporting that ocean indicators of La Niña have returned to neutral levels, while atmospheric indicators that remain at La Niña levels have started to weaken.

All but one of the surveyed international climate models suggest sea surface temperatures in the tropical Pacific (including NINO3.4) will remain neutral (neither El Niño nor La Niña) through autumn; one model is neutral in March and April but touches on El Niño thresholds in May. ENSO outlooks extending beyond autumn should be viewed with caution as models typically have lower forecast accuracy at this time of year.

The Madden–Julian Oscillation (MJO) is forecast to strengthen over the western Pacific at the start of March and then move to the central then eastern Pacific over the coming fortnight. This may contribute to monsoonal and cloudy conditions over far northern Australia over the coming week, but drier conditions are expected as the MJO moves further east. Westerly wind anomalies associated with the MJO may also weaken the trade winds in the tropical Pacific, contributing to the further breakdown of La Niña.

The Southern Annular Mode (SAM) index is currently positive, but is expected to return to neutral values over the coming weeks.

Warmer than average sea surface temperatures persist around south-east Australia, New Zealand and the west coast of Australia, but have returned to close to average temperatures in waters to Australia’s north.

Climate change continues to influence Australian and global climates. Australia’s climate has warmed by around 1.47 °C over the period 1910–2021. There has also been a trend towards a greater proportion of rainfall from high intensity short duration rainfall events, especially across northern Australia. Southern Australia has seen a reduction of 10 to 20% in cool season (April–October) rainfall in recent decades.

Source: BOM