Weekly Tropical Climate Note

Suppressed tropical rainfall to Australia's north during coming week

The Madden–Julian Oscillation (MJO) was weak or indiscernible during the past week, although some (but not all) climate models predict it may strengthen slightly over the western Indian Ocean in the coming week. Whether or not the MJO does strengthen, it is not expected to significantly influence tropical rainfall patterns across the Maritime Continent during the next fortnight.

Consistent with recent rainfall outlooks, rainfall across the Maritime Continent is expected to be below normal for the coming months. In the absence of short-term climate drivers, including the MJO, which can temporarily increase the likelihood of enhanced rainfall across a particular region, an extended period of below-average rainfall is predicted for much of the region.

Read more about the Bureau's MJO monitoring.

Indian Ocean temperature pattern is dominant climate driver across Australian region

The sea surface temperature (SST) pattern evident across the Maritime Continent and northern Australia, and adjacent ocean basins, appears to be the primary climate driver influencing rainfall across much of Australia and the tropical region to its north. The recent pattern, where average to cooler-than-average SSTs are apparent across waters to Australia's north and warmer-than-average SSTs are seen across the Indian Ocean, is forecast to continue for the next few months. This pattern is consistent with a positive Indian Ocean Dipole and typically leads to drier than normal conditions across much of northern Australia during the southern hemisphere winter and spring period, extending into the early part of the northern Australian wet season (typically, October to mid-December).

As well as a warm Indian Ocean, SSTs in the western and central Pacific Ocean are above average and are predicted to remain so for the coming months. With large swathes of warmer-than-average waters either side of northern Australia, and average to cooler-than-average waters locally across the region, cloudiness and rainfall is likely to be below average across northern Australia and much of the Maritime Continent for the next few months.