Tropical Climate Update

Australian region

Recent conditions

For the week ending 22 December, hot and humid conditions resulted in daily thunderstorms and showers across much of the tropical north, tropical low 07U generated heavy rainfall in some areas around the Gulf of Carpentaria (see section below for details on tropical low 07U), while onshore airflow brought rainfall to Australia's north-east.

Weekly rainfall totals of 100 mm to more than 200 mm were recorded in parts of the southern Gulf of Carpentaria coast and adjacent inland areas, and totals of 15 to 100 mm, locally higher, were recorded in northern parts of Western Australia, much of northern and eastern Northern Territory and large parts of Queensland. The highest weekly total was 343.2 mm at Mornington Island Airport (Queensland), and the highest daily total was 148.0 mm at Centre Island (Northern Territory) in the 24 hours to 9 am on 20 December. 

During the week, low-intensity to severe heatwave conditions started to develop across southern parts of the Northern Territory extending into Western Australia.

Maximum temperatures were below average across large parts of northern Australia on most days during the week. Daily maximum temperature anomalies were up to 4 °C below average across large parts of the tropics, with some localised areas up to 8 °C below average on some days.

Fortnightly forecast

The forecast for the fortnight of 27 December to 9 January, issued on 22 December, shows rainfall is likely to be above average for most of tropical Western Australia, the Top End in the Northern Territory and far north of the Cape York Peninsula in Queensland. Rainfall is likely to be below average for parts of central Queensland.

Maximum temperatures are likely to be below average across northern parts of Western Australia and the Northern Territory, and much of central Queensland. Minimum temperatures are likely to be above average across most of Western Australia and the Northern Territory, and far north-eastern Queensland.

Madden–Julian Oscillation

The Madden–Julian Oscillation (MJO), as of 20 December, is weak or indiscernible. Most forecasts from surveyed models suggest that over the coming week the MJO is likely to remain weak. Beyond the first week of January, there is little agreement as to how the MJO will develop.

Australian monsoon onset

Monsoonal conditions are developing over the southern Indian Ocean and across Australian longitudes. Conditions are currently relatively weak over northern Australia but expected to strengthen in the coming days. There is a high probability that the official onset of the Australian Summer Monsoon (measured at Darwin) will occur in the next day or two.

The Top End of the Northern Territory and regions adjacent to the Gulf of Carpentaria are most likely to observe the strongest monsoon conditions during this current active monsoon burst, which is expected to weaken by early January.

Severe Tropical Cyclone Bakung

Tropical low 05U formed on 11 December to the west of Sumatra, strengthened rapidly reaching tropical cyclone intensity on 12 December and was named Bakung. On 14 December, Bakung peaked at category 3 intensity (Severe Tropical Cyclone) as it moved into the north-west corner of Australia's Area of Responsibility tracking west-south-westwards. Bakung started to weaken on 15 December while changing direction of movement and was downgraded to a tropical low late on 17 December. On 18 December, ex-Tropical Cyclone Bakung left the Australia's Area of Responsibility while slowly dissipating. It did not have any direct impact on the Cocos (Keeling) Islands.

Tropical Cyclone Grant

A tropical low 03U started developing in the Timor Sea from 11 December, before tracking south-westward into the Indian Ocean staying well to the north-west of Western Australia's Pilbara coast. Moving westward it passed to the south of Christmas Island on 20 December bringing heavy rainfall to the island. 03U continued to slowly intensify, reached a tropical cyclone strength (Category 1) on 23 December and was named Grant. Tropical Cyclone Grant continued to move westward and is expected to intensify into a Category 2 system and pass close to the Cocos (Keeling) Islands later on Christmas Eve or during Christmas Day.

Tropical low 07U

Tropical low 07U started  to develop in the northern Arafura Sea on 15 December. It moved slowly south towards northern Australia and approached the north-east Top End coast (Northern Territory) on 18 December, bringing increased shower and storm activity. 07U continued to move southward towards the southern Gulf of Carpentaria coast and on 20 December, it crossed the coast between Port Roper and Port McArthur (Northern Territory). 07U brought heavy rainfall to the coastal and adjacent inland areas of the Carpentaria (Northern Territory) and Gulf Country (Queensland) districts. The highest daily rainfall total during this event was 148.0 mm at Centre Island (Northern Territory) in the 24 hours to 9 am on 20 December.

International conditions

The negative Indian Ocean Dipole (IOD) event, which was active since August 2025, has ended with the IOD index now back to neutral levels (between -0.4 °C and +0.4 °C). The Bureau's model predicts the IOD is likely to remain neutral until at least the end of autumn 2026.

La Niña continues in the tropical Pacific. Forecast models indicate a return to ENSO-neutral conditions is likely in early 2026. 

See the Southern hemisphere monitoring page for details of the current La Niña event.