Climate outlook for July to October 2020

Climate outlook overview

Direct link to the Bureau Climate update

• July rainfall is likely to be below average for southwest WA, parts of southeast Australia, and parts of the far northern tropics. Parts of western and southeastern WA are likely to be wetter than average.
• August to October turns wetter in the east, with the three month period likely to be wetter than average for much of the eastern two-thirds of mainland Australia. Western Tasmania is likely to be drier than average.
• Both days and nights during July to September are likely to be warmer than average across Australia.
• The tropical Pacific Ocean is expected to approach La Niña levels over the coming months. Warmer than average waters are likely in much of the central and eastern Indian Ocean. In the shorter-term, higher pressure is likely to continue to dominate much of Australia during late June and early July.

Wetter months likely for late winter to early spring

• The fortnight 29 June to 12 July is likely to be drier than average for most of Australia (mostly 60–75% chance, greater than 75% chance in parts of the inland southeast). However, there are close to equal chances of a wetter or drier fortnight in much of western and southeastern WA, western Tasmania, and parts of the eastern seaboard.
• However, looking longer-term, August to October is likely to be wetter than average for most of the eastern mainland, the NT, SA, and parts of western and southeastern WA (60–80% chance). Western Tasmania is likely to be drier than average (65–75% chance).
• The northern Australian dry season spans May through September. Tropical northern Australia typically has very low rainfall totals during the dry season, and only a small amount of rainfall is needed to exceed the median.

Warmer days and nights for most of Australia

• Daytime temperatures for the next two weeks (29 June to 12 July ) are likely to be warmer than average for most areas; likely 2–4 degrees warmer than usual for much of the northwest and northern Interior of WA, and up to 2 degrees warmer than average for the remainder of Australia.
• For 29 June to 12 July, nights are likely to be warmer than average for the west, north, eastern seaboard, and Tasmania. Chances of warmer or cooler nights are roughly equal for much of the inland southeast and SA.
• Days during July to September are very likely to be warmer than average across most of Australia (greater than 80% chance for the northern half of Australia, mostly 70–80% in other parts).
• Likewise, night-time temperatures for July to September are very likely to be warmer than average for Australia (generally 65–80% chance for southeast SA, much of Victoria, and inland southern to southwestern NSW; greater than 80% chance elsewhere).

Maximum temperature maps

Minimum temperature maps

Climate influences

• The central and eastern tropical Pacific Ocean is expected to cool in the coming months. Most models anticipate this cooling will approach La Niña thresholds by early spring. As a result, the Bureau's ENSO Outlook has shifted to La Niña WATCH, indicating that the chance of La Niña forming in 2020 is around 50%—roughly double the normal likelihood.
• La Niña typically means a wetter than average winter and spring for much of central, northern, and eastern Australia, with cooler days for much of the continent.
• While waters to the northwest of Australia and in the tropical eastern Indian Ocean are forecast to warm—typical of a negative Indian Ocean Dipole (IOD) event—the Bureau's model suggests a neutral IOD is most likely for the coming months. However, half of the international models surveyed by the Bureau suggest a negative IOD may form in late winter or spring.
• A negative IOD typically brings above average winter–spring rainfall to southern Australia.
• Higher than average air pressure associated with a weakly positive Southern Annular Mode (SAM) is likely to favour drier than average conditions in the southeast during 29 June to 12 July.
• Australia's temperature and rainfall variability are also influenced by global warming caused by human activities. Australia's climate has warmed by around 1.4 °C since 1910, while southern Australia has seen a reduction of 10–20% in cool season (April–October) rainfall in recent decades.
• The Bureau's climate model uses the physics of our oceans, ice and land surface combined with millions of observations from satellites and on land and sea. As a result, it includes the influence of climate change and natural climate drivers like ENSO, IOD, the MJO and SAM in its outlooks.