Tropical Climate Update

Mostly dry across the tropical north

May is the first month of the northern Australia's dry season which lasts until the end of September and is characterized by generally low rainfall. During the fortnight ending 19 May, rainfall totals greater than 25 mm were recorded in a small area spanning the border between Western Australia and the Northern Territory, the far east of the Northern Territory's Top End and some isolated areas in eastern Queensland. Rainfall totals in excess of 50 mm were recorded in small areas of the north-eastern Queensland coast.  Most of tropical Australia recorded little to no rain during the past fortnight.

May rainfall is currently tracking near average across most of tropical Australia, with above average rainfall only recorded in the Top End and central-western parts of the Northern Territory and far northern Queensland. Mean maximum temperatures during May to date have been near average for much of the northern half of the Northern Territory, northern Western Australia and north-western Queensland, while mean minimum temperatures have been above average to very much above average (in the warmest 10% of all Mays since 1910) across most of the tropical north.

Fortnightly forecast

The forecast for the fortnight beginning 24 May, issued on 19 May, indicates that rainfall is likely to be above average along the north-eastern Queensland coast. Below average rainfall is forecast for northern Western Australia and parts of inland Queensland. Rainfall in the northern half of the Northern Territory is likely to be in the typical range for this time of year. For the week beginning 24 May, parts of the Northern Territory and Queensland are likely to see above average rainfall. Both maximum and minimum temperatures are likely to be above average across almost all northern Australia.

Out-of-season tropical lows

Tropical low (33U) formed on 9 May in the northern Arafura Sea, near the coast of West Papua. It slowly moved to the west-north-west, remaining well north of the Northern Territory and exited the Australian region on 13 May.

A weak tropical low (34U) developed on 14 May south-west of the Solomon Islands. It tracked to the south, remaining over open waters well to the east of Australia before dissipating on 15 May.

Madden-Jullian Oscillation (MJO)

As of 17 May, the Madden-Jullian Oscillation (MJO) was indiscernible. Most forecasts from surveyed international models suggest the MJO is likely to remain weak or indiscernible in the coming fortnight. Rainfall patterns across northern Australia are not expected to be influenced by the MJO in the coming fortnight.

Indian monsoon close to onset

The onset of the annual Southwest Monsoon is expected to occur in the coming week. Measured at the far southern Indian state of Kerala, the normal onset date is 1 June. With the northernmost extent of the monsoon currently further north than usual, the 2025 monsoon is likely to commence a handful of days earlier than the long-term average. The Indian Meteorological Department is expecting the overall monsoon seasonal (June to September) rainfall across India to be slightly higher than average in 2025.

For updates on India's Southwest Monsoon onset, go to the Monsoon Information Onset | India Meteorological Department