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Seasonal conditions: December quarter 2018

Matthew Miller

A return to average rainfall provides mixed benefits. Unfavourable summer rainfall outlook for northern Australia. 

Climatic conditions in major crop-producing countries

As at 28 October 2018, global production conditions were generally favourable.

Grains

Conditions for winter wheat production are generally favourable for southern hemisphere countries except Australia. Sowing of winter wheat in the northern hemisphere is continuing under favourable conditions.

Growing conditions for maize in the northern hemisphere are exceptional in parts of the United States, southern Europe and Ukraine. Sowing in the southern hemisphere is beginning under favourable conditions.

Growing conditions are mostly favourable for major rice-producing countries but are mixed for Indonesia, Thailand and the Philippines.

Oilseeds

Soybean growing conditions are exceptional across most of the United States and generally favourable throughout the rest of the northern hemisphere.

Crop conditions, AMIS countries, 28 October 2018

As of this date, global production conditions for wheat, maize, rice and soybeans were generally favourable. 

AMIS Agricultural Market Information System.
Source: AMIS

Climate outlook for Australia

Return to average rainfall provides mixed benefits

The first 9 months of 2018 were marked by particularly dry weather for much of south-eastern Australia (Map 1). Rainfall for the first 9 months of 2018 was the 2nd lowest for the Murray–Darling Basin, 3rd lowest for New South Wales and 8th lowest for Victoria since 1900.

Map 1 Rainfall percentiles, Australia, 1 January to 30 September 2018

Note: Rainfall for January to September 2018 relative to the long-term record and ranked in percentiles. This analysis ranks rainfall for the selected period compared with the historical average (1900 to present) recorded for that period.
Source: Bureau of Meteorology

September 2018 was an exceptionally dry month, especially across southern Australia. September rainfall was the lowest on record nationally and for southern Australia (south of 26°S). It was the 2nd driest September on record for Victoria, 3rd driest for Western Australia and 4th driest for South Australia.

Rainfall during October and November 2018 was generally average to above average across much of Australia. Rainfall for November was slightly above average for Australia as a whole (Map 2).

Map 2 Rainfall percentiles, Australia, 1 to 30 November 2018

Note: Rainfall for November 2018 relative to the long-term record and ranked in percentiles. This analysis ranks rainfall for the selected period compared with the historical average (1900 to present) recorded for that period.
Source: Bureau of Meteorology

November 2018 rainfall was generally average for most cropping regions. However, parts of eastern and northern Queensland recorded below average rainfall.

The return to average rainfall levels during mid to late spring benefited winter crop prospects in southern New South Wales, the southern Wimmera in Victoria, southern South Australia and Western Australia. However, it arrived too late in other regions to benefit winter crops. October rainfall came too late to compensate for the damage resulting from unfavourable seasonal conditions during September.

Summer crop planting in Queensland and northern New South Wales has increased following favourable late spring rainfall.

Increased rainfall leads to improvements in soil moisture

A return to average rainfall totals during October and November 2018 has resulted in an increase in soil moisture levels. This has led to improvements in pasture growth and benefited winter and summer crop prospects.

In November 2018 relative root zone soil moisture was average to well above average across most of Australia for this time of year. However, it was well below average to extremely low across parts of eastern New South Wales, large areas of Victoria and south-western Australia (Map 3).

Map 3 Modelled root zone soil moisture, Australia, 1 to 30 November 2018

Note: Soil moisture estimates are relative to the long-term record and ranked in percentiles. Estimates are used to compare root zone soil moisture during November 2018 and ranked by percentiles for each November in the 1911–2015 historical reference period. Root zone soil moisture is defined as the soil surface to 1 metres in depth.
Source: Bureau of Meteorology

Pasture growth remains below average in eastern Australia

For the 3 months to November 2018, modelled pasture growth was well below average to extremely low across large areas of central and western New South Wales, Victoria, parts of central and northern Queensland, and eastern South Australia. (Map 4).

Map 4 Relative pasture growth, Australia, 1 September to 30 November 2018

Note: AussieGRASS pasture growth estimates are relative to the long-term record and shown in percentiles. Percentiles rank data on a scale of zero to 100. This analysis ranks pasture growth for the selected period against average pasture growth for the long-term record (1957 to 2016). Pasture growth is modelled at 5km2 grid cells.
Source: Queensland Department of Science, Information Technology and Innovation

A return to average rainfall levels during mid to late spring benefited pasture production in parts of northern, central and eastern New South Wales, southern Queensland, northern South Australia, Western Australia and the Northern Territory.

However, it arrived too late to benefit pasture production across large areas of south-eastern Australia, where the temperate pasture species tend to have lower growth rates at this time of year.

Improved outlook for the south, but mixed for northern Australia

The Bureau of Meteorology's climate outlook for December 2018 to February 2019 indicates that a drier than average summer is more likely for much of Queensland, the northern half of Western Australia and parts of the Northern Territory. Conditions for much of the remainder of the country are not expected to be wetter or drier than average (Map 5).

Map 5 Rainfall outlook, Australia, December 2018 to February 2018

Note: Shows the likelihood, as a percentage, of exceeding the 1990–2012 median rainfall for the upcoming 3 months. Median rainfall is defined as the 50th percentile calculated from the 1990–2012 reference period.
Source: Bureau of Meteorology

Development towards El Niño in the tropical Pacific Ocean continues, with outlooks suggesting El Niño is likely to form during the summer months. This would typically bring drier conditions to parts of northern Australia and reduce the chance of rainfall in drought-affected areas in south-east Australia. An ElNiño is also likely to bring warmer than average days to large parts of the continent.

A positive Indian Ocean Dipole (IOD) event is dominating Australia's weather and climate patterns, but it is likely to decay by early summer. From December to April, the IOD typically has little effect on Australian climate.

Summer crop planting in Queensland and northern New South Wales increased following favourable late spring rainfall. However, plantings are likely to be constrained in most regions if current low levels of soil moisture persist and rainfall is absent during the summer crop planting period.

Insufficient summer rainfall could affect pasture growth rates across northern Australia. If realised, this would result in reductions in herd and flock numbers and continuing high fodder prices across eastern Australia.

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Last reviewed:
11 Dec 2018