Tropical Climate Update

Thunderstorms and showers scattered in northern Australia

Although monsoonal conditions are still absent in the northern Australia to date, scattered thunderstorms and showers were recorded across northern Australia during the past fortnight. Weekly rainfall totals (ending 6 January 2025) of 50 mm to 150 mm were recorded in the northern and eastern parts of Queensland, in the Top End of the Northern Territory, and isolated areas of north-west Western Australia.

The long-range forecast for the fortnight of 11 to 24 January 2025 indicates rainfall is likely to be above average across most of Western Australia away from the west coast, and the northwestern, central and southern Northern Territory. However, northern Queensland is likely to receive below average rainfall for the coming fortnight.

Tropical low (09U) in the Northwestern Australian Region 

A tropical low (09U) has formed to the southeast of Christmas Island on Monday 6 January. The 7-day tropical cyclone outlook (for the 7 days ending 13 January) indicates the tropical low (09U) is likely to maintain westward movement and pass south of both Christmas Island and Cocos Islands. There is a moderate chance (25–35%) of 09U to develop into a tropical cyclone as it moves to the southwest of Christmas Island in a few days . The chance reduces to low (less than 15%) from 11 January as 09U moves to unfavourable environmental conditions for development.

For the latest warnings and advice on potential tropical low development, please see the Tropical cyclone 7-day forecast.

Madden–Julian Oscillation weakens in the Western Pacific

The Madden–Julian Oscillation (MJO) has moved slowly across the Western Pacific and weakened in the past fortnight. It is currently indiscernible and near-stationary (as at 4 January 2025).

International climate models suggest that the MJO pulse will re-strengthen and move across the equatorial Africa and Indian Ocean during mid-January. 

At this time of the year, an active MJO in the African and Indian Ocean region is typically associated with increasing convection and cloudiness extending across the Indian Ocean. The tropical cyclone risk is also typically elevated in the southern Indian Ocean. However, the supressed convection and the absence of monsoonal rainfall may remain in northern Australia and the Maritime Continent (MC) in the coming fortnight.  If the MJO continues to move eastward at the typical pace to the eastern Indian Ocean and then MC, as some models suggest beyond the coming fortnight, the MJO is likely to bring a westerly wind burst and enhanced convection to northern Australia and surroundings in late January and the start of February. With this phase of the MJO, this means there is also an increased likelihood of monsoon onset at Darwin towards the end of January. Historically, the average monsoon onset date is the last week of December (centered on 28 December). A monsoon onset date in January is regarded as later than normal. The latest monsoon onset date at Darwin since records began in 1957–58 was in the 1972–73 wet season, on 25 January 1973.