Australia’s weather bureau has officially declared El Nino is underway, as sea surface temperatures rise above thresholds in the central tropical Pacific and atmospheric indicators align with the climate pattern.

The conditions suggest the ocean and atmosphere are reinforcing the El Nino – Southern Oscillation (ENSO) state, which is predicted to strengthen and remain until at least the end of the year.

While Bureau of Meteorology (BOM) forecasts indicate one of the strongest El Nino events since 1950, it does not necessarily mean it will have a strong impact on Australia’s climate.

A BOM spokesman said ENSO was only one of many factors that influenced Australia’s seasonal weather and climate.

“El Nino events are part of a natural cycle in the Pacific Ocean that can affect global weather,” they said.

It usually means central and eastern parts of the nation will experience a drier winter and spring, but it can vary with the last event occurring from spring 2023 to early 2024.

“August to October 2023 was Australia’s driest three-month period on record. A strong positive Indian Ocean Dipole (IOD) also contributed to the dry conditions,” the spokesman said.

“El Nino had less influence from late 2023. Storms along the east coast and four tropical cyclones brought above average rainfall to widespread areas during the summer months.”

A spokesman said long-range forecasts for July to September showed rainfall was likely to be below average for southern and eastern parts of Australia and temperatures would likely be above average in most areas, except the north.

BOM explained El Nino had a dry influence on rainfall patterns, but other factors could boost or reduce this effect.

“Past El Nino events have often coincided with less rainfall in winter and spring, particularly in the eastern half of Australia, higher daytime temperatures in southern areas and increased frost risk due to clearer skies,” the spokesman said.

“However, in a warming climate, past patterns are less reliable as a predictor of future impacts.

“Every El Nino is different no two events are the same.”

El Nino events usually last between six and 12 months, but in some cases it has persisted for up to two years with current forecasts showing the weather pattern will likely stay until the latter part of the year.

“It’s too early to say what summer will be like. The outlook will become clearer by late spring,” the spokesman said.

“El Nino can increase the risk of extreme temperature shifts, like heatwaves and hotter days.

“A warming climate increases the likelihood of hotter conditions, heatwaves, marine heatwaves, fire weather, heavy rainfall and flooding events.

“Most of the southern half of Australia has had above average temperatures so far this yea, but it’s too soon to know how 2026 will play out.”