Climate outlook for July to September

Issued 25 June 2015

Climate outlook overview

A generally wetter-than-average season is more likely for parts of the west, while drier in the far southeast. For most of the country, warmer nights are likely, with warmer days likely for the southern coastline and parts of northern Australia.
The current outlook reflects anomalously warm sea surface temperatures in the Indian Ocean and El Niño in the Pacific (see the climate influences section for more information).

There is an increased chance of a drier three months over southern parts of southeast Australia, but an increased chance of a wetter three months over central and northern WA, as well as adjacent areas over the WA border. Most of eastern Australia has a roughly equal chance of a wetter or drier July to September.
The current outlook reflects anomalously warm sea surface temperatures in the Indian Ocean and El Niño in the Pacific.
Historical outlook accuracy for July to September is moderate over most of Australia, except along the WA border, parts of SA, and areas surrounding the Gulf of Carpentaria, where accuracy is low.

July to September days are likely to be warmer than average across the southern coastline of mainland Australia, Tasmania, and large parts of northern Australia. Overnight temperatures are likely to be warmer than normal for most of Australia, except for an area across the SA-NSW-Victorian border.
Significantly warmer-than-average sea surface temperatures in the Indian Ocean, and those nearer to Australia are likely influencing the warmer overnight temperatures expected for much of the country.
Maximum temperature accuracy is moderate to high over most of Australia. Minimum temperature accuracy is moderate over the northern half of Australia and Tasmania, but generally low to very low elsewhere.

El Niño persists in the tropical Pacific Ocean, and has seen reduced cloud cover and rainfall to Australia's north. Sea surface temperatures (SSTs) in the Indian Ocean remain notably warmer than average. The combination of these two influences is tending to increase the chances of above-average rainfall across WA, and resulting in roughly equal chances of a wetter or drier three months for the eastern half of the country. The combination of a warm Pacific and warm Indian Ocean represents an unusual set of circumstances.
Climate models suggest that the tropical Pacific will remain above El Niño levels for the outlook period.
Three out of five international models suggest an increased chance of a positive Indian Ocean Dipole (IOD) event developing later in 2015. Positive IOD events are typically associated with decreased winter-spring rainfall over southern and central Australia.
The Australian tropics are now in their dry season; much of this region receives less than 10 mm of rain on average over the cooler months.
Bureau climatologists continually monitor the climate for any significant developments, with information on El Niño/La Niña and IOD events available fortnightly via the ENSO Wrap-Up. For a summary of Pacific and Indian Ocean outlooks, please see the Climate Model Summary.