Climate outlook for August to October

Issued 30 July 2015

Climate outlook overview

A neutral rainfall outlook for most of the country, though drier conditions are favoured in the tropics and far southeast, with a wetter-than-average season more likely in the west. Warmer nights are very likely for most of Australia, along with warmer days for much of the east and the southern coastline.
The current outlook reflects the much warmer-than-average sea surface temperatures in the Indian Ocean, and El Niño in the Pacific (see the climate influences section for more information).

Odds are raised for a drier-than-average three months over southern parts of southeast Australia, the Top End of the NT and the northern Cape York Peninsula in Queensland. Conversely, there is an increased chance of a wetter three months over central and southern WA, as well as adjacent areas over the WA border. Most of eastern Australia has a roughly equal chance of a wetter or drier August to October.
The current outlook reflects considerably warmer-than-average sea surface temperatures in the Indian Ocean and El Niño in the Pacific.
Historical outlook accuracy for August to October is moderate to high over most of Australia, except in central and southwest parts of WA, parts of southern Queensland, and eastern NSW, where accuracy is low.

August to October days are likely to be warmer than average across northeastern Australia, Tasmania, and the mainland's southern coastline. Overnight temperatures are likely to be warmer than normal for most of Australia except for the far north.
Significantly warmer-than-average sea surface temperatures in the Indian Ocean and seas close 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, except for a large area extending from northern WA through to western Queensland, where accuracy is low to very low. Minimum temperature accuracy is low to moderate over the northern half of Australia, SA and Tasmania, but low to very low elsewhere.

El Niño persists in the tropical Pacific Ocean, and has seen reduced cloud and rainfall to the north of Australia. Sea surface temperatures (SSTs) in the Indian Ocean remain significantly warmer than average, while SSTs around Australia are average to above average. The combination of these influences is tending to increase the chances of above-average rainfall across WA, while producing roughly equal chances of a wetter or drier three months for the eastern half of the country. The combination of a warm Pacific (generally associated with drier conditions for Australia) and warm Indian Ocean (generally associated with wetter conditions) represents an unusual set of circumstances, and has been in place for a number of months now.
Climate models suggest that the tropical Pacific will remain well above El Niño levels for the outlook period.
Currently, the Indian Ocean Dipole is neutral. 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.
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.