Tropical Climate Update

Australian wet season wrap-up

The northern wet season (1 October to 30 April) for 2018-19 was characterised by below-average rainfall across northern Western Australia and the Northern Territory, with above-average rainfall for tropical Queensland. Overall, rainfall cross northern Australia was 16% below the long-term average, the lowest since 2005. Rainfall was strongly influenced by monsoonal activity and the associated tropical low and tropical cyclone activity. Monsoonal rainfall across the western two-thirds of northern Australia was late to commence and relatively weak with respect to its impacts. In contrast, Queensland finished the season with high rainfall totals from several tropical lows and cyclones. Most significantly, tropical cyclones Penny, in early January, and Trevor, during March, in addition to a predominantly land-based tropical low which was active from late January to early February, led to widespread flooding across multiple regions of Queensland during the wet season. In contrast, there was minimal direct impact by tropical cyclones across the Northern Territory's Top End and Western Australia. A late monsoon onset date of 23 January at Darwin, the equal-third latest on record, also contributed to drier than usual conditions over northwestern Australia.

Tropical cyclone numbers were marginally below average overall, with nine systems during the season, compared to the average of 10-13 across the Australian region. The number for Western Australia, typically the most active part of the Australian region for tropical cyclones, was below the average of seven, with only five tropical cyclones in 2018-19 and no coastal crossings, although Veronica came very near to Western Australia's Pilbara coast and generated flooding rains in the Port Hedland region in the last week of March. In total, three Australian tropical cyclones made landfall, compared to the average of four coastal crossings per season. Veronica was the strongest tropical cyclone in the Australian region during 2018-19, with a peak intensity of category 4 and maximum sustained winds estimated at 195 km/h.

The Gulf of Carpentaria saw three tropical cyclones, Owen, Penny and Trevor, with Trevor being the most intense Australian system to make landfall during the 2018-19 season. Overall, both the Northern Territory and Queensland had four tropical cyclones move over their regions during the season. This is equal to the average number of systems for Queensland, and slightly above the Northern Territory average of between 2 and 3 tropical cyclones per season. 

Tropical cyclone reports and maps are available at the Bureau's Severe Weather Events page.

Madden–Julian Oscillation moves to western Pacific Ocean

After contributing to above-average rainfall across much of Indonesia, Papua New Guinea and parts of far northern Australia during the last fortnight, a pulse of the Madden–Julian Oscillation (MJO) recently moved out of the Maritime Continent and into the West Pacific region. At this time of the year, once the MJO tracks east of the Maritime Continent, rainfall typically returns to average across northern Australia. As the MJO tracks even further east into the central Pacific, as currently indicated by climate models, a period of suppressed rainfall typically develops over far northern Australia and the broader Maritime Continent.

During the dry season months of May to September, a climatologically low-rainfall period for most of tropical Australia when broadscale climate factors are conducive to dry conditions, the influence of the MJO is significantly less than during the wet season months.

Read more about the Bureau's current MJO monitoring.