Climate outlook for summer (December to February)

Issued 16 November 2017

Climate outlook overview

The rainfall outlook for summer (December to February), issued 16 November 2017, shows northeast NSW and regions surrounding the Gulf of Carpentaria are likely to be drier than average. There is no strong shift towards a wetter or drier summer across the rest of the country.
Summer daytime and overnight temperatures are likely to be warmer than average for most of the eastern two-thirds of Australia.
Australia's major climate drivers are neutral, but a La Niña WATCH remains in place due to recent cooling in the eastern tropical Pacific. Sea surface temperature patterns in the western Pacific and eastern Indian Ocean are not typical of La Niña, and are counteracting its normally wet signal. See the Climate Influences section for more information.

The rainfall outlook for summer shows northeast NSW and regions surrounding the Gulf of Carpentaria are likely to be drier than average. Elsewhere across the country, there is no strong signal showing wetter or drier conditions for summer.
December is likely to be drier than average for parts of the WA coast, and areas surrounding the Gulf of Carpentaria and Cape York Peninsula.
Australia's major climate drivers remain neutral. La Niña WATCH is currently in place due to recent cooling in the eastern tropical Pacific. However, sea surface temperature patterns in the western Pacific and eastern Indian Ocean are likely to counteract the typical (wetter) effects of a cooling Pacific Ocean.
Historical outlook accuracy for summer is moderate for eastern and western parts of Australia, but generally low elsewhere. See map for more detail.

Summer daytime and overnight temperatures are likely to be warmer than average for most of the eastern two-thirds of Australia.
For December, parts of the north and most of the southeast are likely to have warmer than average days and nights. Overnight temperatures are also likely to be warmer than average in central Australia but cooler than average along parts of Queensland's east coast.
Historical accuracy for maximum temperatures is moderate over most of Australia, except the southern NT, SA, Victoria and eastern NSW, where accuracy is low. Minimum temperature accuracy is moderate for most of Australia except the central NT and parts of the southeast.

The current ENSO Outlook is at La Niña WATCH. Most models suggest the tropical eastern Pacific Ocean will continue to cool, and may reach or exceed La Niña thresholds during the summer.
Typically when the tropical Pacific cools towards La Niña levels, the western Pacific and seas around northern Australia warm significantly, but models suggest this is unlikely to occur.
Likewise, warmer than average waters typically develop in the eastern Indian Ocean during La Niña. This season, near average to cooler waters are forecast to remain in this area, while warmer waters remain off Africa.
The opposing rainfall signals from the ocean patterns surrounding us (neutral to dry from the north and west versus a wet signal from the east) is likely the reason why Australia does not have increased chances of a wetter and cooler summer.
In addition to the natural drivers such as the El Niño–Southern Oscillation and the IOD, Australian climate patterns are being influenced by the long-term increasing trend in global air and ocean temperatures.
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.