The Bureau of Meteorology's summer outlook lands in late October, with El Nino at near-record levels and a positive Indian Ocean Dipole likely to develop.
Lifestyle Desk is a contributing writer covering city and public affairs for The Sydney Times.
The Australia summer weather outlook for December to February has not been published as of 11 October, but the climate drivers behind it are already flashing warning signs. The Bureau of Meteorology declared an El Nino in June 2026 and now rates it at near-record levels, with a positive Indian Ocean Dipole likely to develop through spring. The Bureau's long-range outlook for the three summer months is due in late October, and it will set the national tone for heat, rainfall and bushfire risk into the new year.
The Bureau's Southern Hemisphere Monitoring update, issued 29 September 2026, puts the relative Nino3.4 index at plus 2.72 degrees Celsius for the week ending 27 September, the second-highest weekly value in records dating back to 2008. The 30-day Southern Oscillation Index stood at minus 20.5, well below the El Nino threshold of minus 7. Trade winds across the western to central tropical Pacific have weakened or reversed, the hallmark of a strong event in the atmosphere as well as the ocean.
Every climate model the Bureau consulted, including its own, forecasts the tropical Pacific to keep warming through spring, likely peaking in late spring or early summer and persisting into autumn 2027. The majority of models indicate a peak above plus 3.0 degrees Celsius, which would exceed the warmest values observed since reliable records began in 1950.
The Indian Ocean Dipole remains neutral, but its index has sat above the positive threshold of plus 0.4 degrees for three consecutive weeks, reaching plus 0.76 degrees in the week to 27 September. The Bureau says a positive IOD is likely to develop during spring and persist into early summer, though model guidance carries uncertainty about its strength and duration. A positive IOD typically brings drier conditions to southern and eastern Australia, and can reinforce the El Nino signal.
El Nino typically tilts Australian summers towards hotter and drier conditions in the east. The Bureau links the pattern to reduced rainfall, particularly in eastern Australia, and increased temperatures, mainly across the country's south. Past strong events have contributed to some of Australia's hottest and driest years on record.
The Bureau itself urges caution. Its September update notes that a strong El Nino signal in the Nino3.4 region does not necessarily mean strong impacts on Australian rainfall and temperature, because ENSO is only one of many factors influencing the nation's seasonal weather. That is precisely why the long-range outlook matters: it blends ocean and atmosphere signals into regional probabilities rather than relying on any single driver.
The fire agencies are not waiting for the summer numbers. The Australasian Fire and Emergency Services Authorities Council (AFAC) released its Seasonal Bushfire Outlook for Spring 2026 in August, predicting an increased risk of fire across all jurisdictions except the ACT. The drivers it cites mirror the Bureau's: dry conditions in the east, increased fuel loads across central and northern Australia, and a strengthening El Nino.
AFAC CEO Rob Webb said the outlook highlighted a heightened risk of fire across several parts of the country, driven by a combination of dry conditions in the east and increased fuel loads through parts of central and northern Australia. The Bureau's Michael Egan, speaking at AFAC26 in Melbourne in August, said the outlook identifies an above-average risk for northern and south-eastern NSW, south-east Queensland, north-eastern Tasmania, parts of Western Australia and Victoria, and large parts of the Northern Territory. The Australia bushfire season 2026 preparation guide sets out the state-by-state risk map in detail.
The Bureau's long-range outlook covers the coming three months, with maps of likely maximum and minimum temperatures and rainfall. The December to February edition, due in late October, will translate the El Nino and IOD signals into the probabilities that matter for summer: how hot, how dry, and where. As of 11 October it has not been published, and no rainfall or temperature forecast for the season should be treated as official until it is.
The outlook is a probability product, not a promise. The Bureau's long-range forecast page provides the best guidance on likely conditions in the coming months, taking into account all influences from the oceans and atmosphere. It shows whether each region is more likely to be wetter or drier than average, and warmer or cooler, over the three months ahead.
Watch the eastern states. With El Nino at near-record levels and a positive IOD likely, the seasonal pattern associated with these drivers skews towards below-average rainfall in the east and above-average heat across the south. The final numbers belong to the October release.
Preparation does not need to wait for the outlook. On heat, the Bureau's monitoring page shows sea surface temperatures up to 3 degrees above average around much of Australia's west, south and south-east, and August 2026 was the warmest month for global sea surface temperatures on record, at 1.04 degrees above the 1961 to 1990 average. Warmer oceans can add moisture and energy to the atmosphere, which can fuel intense rainfall events even in a dry season.
On fire, AFAC's advice is to act early: understand the risk in your area, prepare a bushfire survival plan, clear gutters of dry leaves and debris, and discuss the plan with your household before conditions deteriorate. On water, NSW Government monitoring shows storage levels in the Sydney region, including Warragamba Dam, at adequate levels after a warmer-than-average winter, but a dry El Nino summer is the right time to check tank levels and follow any council restrictions. For Sydney's summer climate norms, the Sydney weather forecast 2026 guide tracks average maximums of 26 to 29 degrees across the season.
Sun safety belongs in the plan too. The Bureau's UV and sun protection guidance applies all summer, and the City climate hub carries the latest Sydney forecasting and heatwave alerts. For broader urban coverage, visit The City hub.
The next Southern Hemisphere Monitoring update will show whether the IOD has crossed into an established positive phase. The summer outlook itself lands in late October. Until then, the Bureau's long-range forecast page remains the best guidance on the season ahead.
Direct inquiries, corrections, or documentation concerning this dispatch to our editorial newsroom desk.
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