BOM declares El Niño underway in the tropical Pacific

The Bureau of Meteorology has declared El Niño underway in the tropical Pacific, shifting the pattern from warning signs to an active event in its June 16 Southern Hemisphere monitoring update.

The bureau said the latest ocean and atmosphere readings now line up with El Niño conditions. Central tropical Pacific sea-surface temperatures are above the usual threshold, trade winds have weakened, cloud and pressure patterns are consistent with the event, and the Southern Oscillation Index has turned sharply negative.

The BOM said the latest Niño3.4 index reading for the week ending June 14 was +0.92C. It said the 30-day Southern Oscillation Index to June 14 was -23.3, which it described as consistent with an El Niño state.

How the event formed

The Australian bureau’s update follows a period of watchful signals rather than a fully formed event. By June 16, it said the indicators had aligned enough to say El Niño was underway in the tropical Pacific.

BOM technical lead for extended prediction Felicity Gamble said the bureau is now seeing the climate markers come together. The agency said the event is likely to strengthen and remain in place until at least the end of the year.

The bureau also said around half of the models it tracks suggest the event could peak among the highest observed since 1950. It warned, however, that a strong El Niño signal does not automatically mean strong impacts for Australia.

What it could mean for Australia

El Niño typically raises the odds of hotter and drier conditions across parts of Australia during winter and spring. That can increase the risk of heatwaves, fire weather and bushfire conditions, and can also contribute to rainfall deficits in southern and eastern areas.

Those are risks rather than guarantees. The BOM stressed that El Niño is only one of several climate drivers affecting Australia, so the eventual weather pattern can still vary from the usual textbook outcome.

The bureau also said the Indian Ocean Dipole is currently neutral. It said a positive IOD is likely during the southern hemisphere winter and spring, but model forecasts vary on both timing and strength.

Why the outlook matters now

Farmers, rural communities and water managers often treat El Niño forecasts as a planning signal, especially when looking ahead to planting, reserves and drought preparedness. Emergency and fire-planning authorities also watch the outlook for shifts in heat and fuel conditions.

The BOM said global sea-surface temperatures were very warm, with May 2026 the warmest May on record since 1900. It said warming oceans and climate change make historical El Niño impacts less reliable as a guide to what happens next.

Timeline and context

The Australian declaration follows a June 11 NOAA announcement that El Niño had officially formed in the Pacific and could become one of the strongest since records began in 1950. The BOM’s update adds local confirmation and a sharper focus on Australian impacts.

For now, the bureau says the key question is not whether El Niño exists, but how strong it becomes and whether other climate drivers amplify or offset its effects over the coming months.