Weekly Australian Climate, Water and Agricultural Update, 24 October 2024

For the week ending 23 October 2024, a humid airmass combined with a series of troughs to bring showers and isolated thunderstorms to parts of northern, central and south-eastern Australia. Rainfall totals of up to 50 millimetres were recorded across Victoria, Tasmania, large areas of New South Wales, and eastern South Australia, and scattered areas of southern Queensland, southern and northern Western Australia and the Northern Territory. Isolated areas of Tasmania and eastern Victoria recorded falls up to 100 millimetres. High pressure systems saw much of the remainder of the country record little to no rainfall.

Across cropping regions, rainfall totals of between 5 and 50 millimetres was recorded across New South Wales, Victoria, eastern and central South Australia, and isolated areas of central Queensland and northern Western Australia. Little to no rainfall was recorded across remaining areas. Across most south-eastern growing regions rainfall totals were higher than what was forecast for the week, and as such a likely to have been sufficient to arrest further reduction in the yield potential of winter crops. In regions where average levels of stored soil moisture were available, crops and pastures would have been able to draw on these reserves to maintain current yield potentials. With the harvest of winter crops in full swing across northern cropping regions, mainly dry conditions across much of Queensland would have provided largely uninterrupted harvest conditions.

Rainfall for the week ending 23 October 2024

Over the 8 days to 24 October 2024, low-pressure and frontal systems are expected to bring showers and storms over parts of northern and eastern Australia. Falls of between 10 and 50 millimetres are forecast for, eastern New South Wales, eastern Queensland and Tasmania. Falls of between 5 and 25 millimetres expected across parts of southern Victoria and parts of northern Western Australia and Queensland, and the Northern Territory. High pressure systems are expected to keep much of, western, central and southern Australia largely dry.

Across cropping regions, some rainfall is expected across north-eastern growing regions, with little to no rainfall expected across most cropping regions. Rainfall totals of between 5 and 50 millimetres are expected in Queensland and north-eastern New South Wales.

If realised, these falls across north-eastern cropping regions are likely to provide a boost to soil moisture levels and assist with the planting of summer crops. However, this forecast rainfall may result in some delays to the harvest of winter crops.

Little to no rainfall forecast across southern Australia will provide for an uninterrupted harvest of winter crops for grain and hay where harvest has commenced. However, as conditions remain dry across large areas of southern Australia, farmers will be continuing to make decisions on whether to cut crops for hay or turn them over for livestock grazing as grain yields and relative returns for grain compared to hay continue to decline.

Total forecast rainfall for the period 24 October to 31 October 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) has been neural for several weeks (as at 13 October). Forecasts indicate it is likely to remain neutral over the coming week. A neutral SAM has no strong relationship to forecast climate conditions.

The most recent rainfall outlook for November 2024 provided by the Bureau of Meteorology indicates that much of New South Wales, Queensland, eastern Victoria, South Australia, the Northern Territory and northern areas of Western Australia are likely to see above median rainfall (between 55 to 70% chance). There is a roughly equal probability of either above or below median rainfall across parts of western, south-eastern and northern Australia.

According to Bureau of Meteorology’s climate model, for November 2024, there is a 75% probability of rainfall totals of between 10 and 50 millimetres across much of eastern and central New South Wales, Victoria, eastern Queensland, the far south-west of Western Australia, eastern agricultural areas of South Australia, and much of the tropical north. Meanwhile, Tasmania and parts of eastern New South Wales, eastern Victoria and the north of the Northern Territory are expected to see falls of between 25 and 200 millimetres. Much of western and central Australia is expected to receive little to no rainfall.

Across cropping regions, there is a 75% chance of receiving between 10 and 50 millimetres of rainfall across much of New South Wales, Victoria and Queensland, with higher rainfall totals expected in north-eastern regions. In South Australia and southern Western Australia, rainfall totals are expected to be between 5 and 25 millimetres. These relatively low expected rainfall totals across much of southern Australia continue to represent a significant downside production risk for both winter crop production and pasture growth, particularly given the lack of rainfall in recent months and declining soil moisture levels across large areas. However, 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 winter and summer crops and average or better levels of pasture production in these states.

Rainfall totals that have a 75% chance of occurring in November 2024

The rainfall outlook for November 2024 to January 2025 indicates no strong tendency toward either above or below average rainfall across much of the country. Below median rainfall is more likely across isolated areas of south-western Tasmania and parts of tropical northern Australia. Meanwhile, above median rainfall in more likely across parts of the eastern seaboard and north-western Western Australia

Across cropping regions, the probability of receiving above median rainfall is between 50% and 65% in New South Wales, Victoria, Queensland and Western Australia. In South Australia there is no strong tendency toward either above or below average rainfall. If above median rainfall is realised, this rainfall is likely to support the storage of soil moisture in eastern regions for the summer cropping period.

Chance of exceeding the median rainfall November 2024 to January 2025

The outlook for November through to January suggests a 75% chance of rainfall totals between 50 and 300 millimetres across much of central and eastern New South Wales, Queensland, Victoria, Tasmania and the Northern Territory, and across parts of Western Australia. Rainfall totals in excess of 300 millimetres are forecast for alpine regions of Victoria and New South Wales, isolated coastal areas of eastern New South Wales and Queensland, western Tasmania and the tropical north of Queensland, Western Australia and the Northern Territory.

In 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 New South Wales and Victoria. Conditions are expected to be drier in Western Australia with forecast rainfall totals of between 10 and 100 millimetres, and in South Australia and Victoria, where falls of between 25 to 100 millimetres are expected.

Given harvest will be well underway across several regions, November through to January rainfall will have little influence on winter crop production prospects, other than its influence on harvest progress. Meanwhile, if the forecast November through to January rainfall totals are realised, they are likely to be sufficient to support late spring and summer pasture growth across eastern and northern Australia. Additionally, these expected falls are likely to be sufficient to maintain above yield expectation for summer crops.

Rainfall totals that have a 75% chance of occurring November 2024 to January 2025