Weekly Australian Climate, Water and Agricultural Update, 12 December 2024

In the week ending 11 December 2024, low-pressure systems brought rainfall and storms to every state and territory. Falls of between 5 and 150 millimetres were recorded across much of the far north of the country, with parts of northern Queensland seeing as much as 300 millimetres. Widespread falls of between 10 and 100 millimetres were recorded across central and eastern areas of the country, including the southern Northern Territory, north-eastern and central regions of New South Wales and Queensland, central Western Australia, northern South Australia, eastern Victoria and western Tasmania. In contrast, high-pressure systems kept the south comparatively dry, with southern Western Australia seeing between 0 and 10 millimetres.

Across cropping regions, rainfall outcomes were mixed, with large areas of Queensland and New South Wales seeing between 10 and 100 millimetres. In the south, rainfall totals were lower, with much of South Australia and Victoria recording between 5 and 10 millimetres of rainfall over the period, and Western Australia remaining largely dry. For those eastern areas that recorded significant rainfall this week, this has likely delayed the harvest of remaining winter crops, but will provide a boost to soil moisture levels benefitting summer crop production in Queensland and pasture growth in central New South Wales.

Rainfall for the week ending 11 December 2024

Over the 8 days to 19 December 2024, low-pressure systems are expected to bring high rainfall totals to the west and north of the country, with falls of between 25 and 100 millimetres likely for much of northern and central Western Australia, the north of Northern Territory, northern and eastern Queensland, as well as western Tasmania. A high-pressure system is likely to keep the south-east relatively dry, with New South Wales and Victoria likely to see between 5 and 10 millimetres of rainfall, and South Australia likely to see between 5 and 15 millimetres.

Across cropping regions, rainfall totals are forecast to be low across the southeast, with heavier falls expected in the north and west. Northern and central Queensland cropping regions are forecast to receive between 25 and 100 millimetres of rainfall, while south-western Queensland, New South Wales, Victoria, and South Australia are expected to see little to no rainfall. Across the north and east of Western Australia, falls of between 10 and 25 millimetres are forecast. If realised, the mainly dry conditions across eastern cropping regions will likely support the harvest of remaining winter crops. Rainfall forecast for summer cropping regions in northern Queensland will likely provide a boost for soil moisture levels and support the germination and growth of crops already in the ground.

Total forecast rainfall for the period 12 December to 19 December 2024

The El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) climate drivers are currently neutral and having minimal influence on Australian rainfall. The Southern Annular Mode (SAM) is currently negative and is forecast to return to neutral conditions in the coming weeks. A negative SAM contributes to a decreased chance of rain in the summer months across south-eastern Australia.

The most recent rainfall outlook for January 2025 provided by the Bureau of Meteorology indicates that much of eastern Australia, including eastern Queensland and New South Wales, as well as parts of Western Australia are likely to see above median rainfall. For the remaining regions, rainfall is likely to be similar to average.

According to Bureau of Meteorology’s climate model, for January 2025, there is a 75% chance of rainfall totals of between 50 and 300 millimetres across much of the north, including northern Western Australia and the Northern Territory, with parts of northern Queensland likely to see as much as 400 millimetres. Lower rainfall totals are expected across eastern areas, with much of southern Queensland, New South Wales, Victoria and Tasmania likely to see between 5 and 100 millimetres. In South Australia and southern Western Australia, little to no rainfall is expected.

Across cropping regions, there is a 75% chance of receiving between 10 and 50 millimetres of rainfall across much of New South Wales with falls of between 25 and 100 millimetres expected in Queensland. Little to no rainfall is expected across remaining cropping regions.

The relatively low expected rainfall totals across much of southern Australia are typical for this time of year. This is likely to lead to continued low levels of pasture growth and increased turn off of livestock for slaughter. In contrast, if forecast rainfall totals are realised across much of New South Wales and Queensland, these falls are likely to be sufficient to support above average yield prospects for summer crops and average or better levels of pasture production.

Rainfall totals that have a 75% chance of occurring in January 2025

The rainfall outlook for January to March 2025 indicates an increased probability of above average rainfall across large areas of eastern and western Australia. Much of the remainder of the country is equally likely to receive above or below median rainfall.

Across cropping regions, the chance of receiving above median rainfall is between 55% to 75% across much of Queensland, with New South Wales, Victoria, and Western Australia having a 55 to 65% chance of above median rainfall. In South Australia, the chances of receiving above or below median rainfall are approximately equal.

Rainfall totals that have a 75% chance of occurring January 2025 to March 2025

The outlook for January through to March suggests a 75% chance of receiving rainfall totals of between 50 and 300 millimetres across much of Queensland, New South Wales, southern Victoria, Western Australia, Tasmania, and the Northern Territory. Rainfall totals in excess of 300 millimetres are forecast for the tropical north of Western Australia, the Northern Territory, and Queensland, as well as coastal areas of Queensland and New South Wales and western Tasmania. The far southwest of Western Australia and much of South Australia are likely to receive rainfall totals of between 10 and 50 millimetres over this period.

In summer cropping regions, there is a 75% chance of receiving between 100 and 300 millimetres of rainfall across much of Queensland, and between 50 and 200 millimetres across northern New South Wales. If realised, these forecast rainfall totals are likely to be sufficient to support summer pasture growth across eastern and northern Australia. Additionally, these expected falls are likely to provide a boost to soil moisture profiles and maintain above yield expectation for summer crops in Queensland and northern New South Wales.

Rainfall totals that have a 75% chance of occurring January 2025 to March 2025