Climate outlook for July to September

Issued 14 June 2018

Climate outlook overview

For the July to September outlook, issued 14 June 2018, northern Australia and the southeast mainland are likely to be drier than average.
Daytime temperatures for July to September are likely to be warmer than average for northern and eastern Australia; nights are likely to be warmer than average for most parts, except the far north.
July is likely to be drier across the eastern half of mainland Australia, with parts of the southeast having a greater than 80% chance of a drier than average month.
The El Niño–Southern Oscillation and the Indian Ocean Dipole are forecast to remain neutral during winter and thus have less influence on Australia's climate.
Higher than average pressures to the south of Australia persist right through the season, resulting in weaker westerlies and fewer cold fronts from the Southern Ocean. See the Climate Influences section for more information.

July to September is likely to be drier than average in the southeast mainland, and in northern Australia, although rainfall totals are typically low at this time of year in the tropical regions.
July is likely to be drier than average across the eastern half of mainland Australia, with parts of the southeast having a greater than 80% chance of a drier than average month.
Historical outlook accuracy for July to September is moderate over eastern Australia and parts of western WA. Elsewhere, accuracy is low to very low. See map for more detail.

July to September days are likely to be warmer than average for northern and eastern Australia. Chances are highest in the southeast of the country, with a greater than 80% chance of warmer days.
July to September nights are likely to be warmer than average for most of Australia, except in the far north. Chances of warmer nights exceed 80% in Tasmania, and along the NSW and Victorian coasts.
Historical accuracy for July to September maximum temperatures is moderate to high for most of Australia. Minimum temperature accuracy for July to September is patchy, with generally moderate accuracy across northern Australia, Tasmania, and coastal regions of SA, Victoria and NSW. Elsewhere, accuracy is low to very low.

The El Niño–Southern Oscillation and the Indian Ocean Dipole are forecast to remain neutral for the rest of winter and thus have less influence on Australia's climate.
While the Bureau's model suggests neutral ENSO beyond winter and into spring, some models suggest El Niño may develop in spring. However, there is a large range of scenarios in the models, with neutral most likely, El Niño possible, and La Niña very unlikely.
When broadscale drivers are neutral, the climate is often influenced by secondary climate drivers or more local effects.
This July to September outlook is for higher than average pressure to the south of Australia, resulting in weaker westerlies and fewer cold fronts from the Southern Ocean affecting southeast Australia.
In addition to the natural drivers such as the El Niño–Southern Oscillation (ENSO) and the IOD, Australian climate patterns are also being influenced by the long-term increasing trend in global air and ocean temperatures. For instance, southern Australia has seen a slow southward shift in autumn/winter frontal systems over the past three decades.
Bureau climatologists continually monitor the climate for any significant developments. See our ENSO Wrap-Up and Climate Model Summary for the latest climate information and forecasts of El Niño, and La Niña and the IOD.