Australia in December 2023

In brief

• For Australia as a whole, total rainfall was 1.9% below the 1961–1990 average for December.

• Rainfall in December was above average for much of northern, eastern and south-western Queensland, most of Victoria and South Australia, parts of southern New South Wales, and areas in south-eastern Western Australia and the western Top End in the Northern Territory.

• Rainfall was below average for large parts of western and northern Western Australia, Northern Territory and north-western Queensland, and for an area of western New South Wales extending into eastern South Australia.

• Australia's national area-average mean temperature was 1.60 °C above the 1961–1990 average, the fourth-warmest December on record.

• The national area-average mean maximum temperature  was 1.92 °C above average. The national area-average mean minimum temperature was 1.27 °C above average.

• Mean maximum temperatures were above average across the Northern Territory and Tasmania, for most of Western Australia, New South Wales and Queensland, large parts of northern South Australia and an area of north-western Victoria. Mean maximum temperatures were below average for parts of coastal South Australia and north-western Western Australia and for an area of central northern Queensland.

• Mean minimum temperatures were above average across New South Wales, Victoria and Tasmania, for much of Western Australia, the Northern Territory and Queensland, and large parts of western and eastern South Australia. Mean minimum temperatures were below average for some coastal areas of Western Australia and an area of southern Northern Territory.

Further information and tables of records for each state and the Northern Territory can be found in the individual regional climate summaries, published on 9 January 2024.

Temperatures

Australia's national area-average mean temperature for December was 1.60 °C above the 1961–1990 average, the fourth-warmest on record (since 1910).

For the Northern Territory it was the third-warmest December on record, for New South Wales and Western Australia it was the fourth-warmest, for Queensland the sixth-warmest and for Tasmania the eighth-warmest December on record.

The nationally averaged mean maximum temperature for December was 1.92 °C above the 1961–1990 average, the fourth-warmest December days on record. Mean maximum temperatures for December were above average across the Northern Territory and Tasmania, for most of Western Australia, New South Wales and Queensland, large parts of northern South Australia and an area of north-western Victoria. Mean maximum temperatures were very much above average (in the highest 10% of Decembers since 1910) for most of Western Australia and the Northern Territory, parts of north-western and south-eastern Queensland, western and north-eastern New South Wales and northern Tasmania. Areas in north-western and central Western Australia had highest on record mean maximum temperatures for December.

Mean maximum temperatures were below average for parts of coastal South Australia and north-western Western Australia and for an area of the central northern Queensland.

The national mean minimum temperature was 1.27 °C above average, the fifth-warmest December nights on record.

Mean minimum temperatures were above average across New South Wales, Victoria and Tasmania, for much of Western Australia, the Northern Territory and Queensland, and large parts of western and eastern South Australia. Mean maximum temperatures were very much above average (in the highest 10% of all Decembers since 1910) for large parts of central and north-western Western Australia, most of the northern half of the Northern Territory, large parts of northern and eastern Queensland, eastern and north-western New South Wales and much of Victoria and northern Tasmania. Mean minimum temperatures were the warmest on record for parts of north-western Northern Territory extending into adjacent areas of north-eastern Western Australia, western Cape York Peninsula in Queensland and north-eastern New South Wales. Some stations had their highest mean minimum temperature on record for December.

Rank ranges from 1 (lowest) to 114 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Anomaly is the departure from the long-term (1961–1990) average.

Rainfall

For Australia as a whole, December rainfall was 1.9% below the 1961–1990 average. 

Rainfall in December was above average for Queensland, New South Wales, Victoria and South Australia, and below average for Tasmania, Western Australia and the Northern Territory.

Rainfall was above average for much of northern, eastern and south-western Queensland, most of Victoria and South Australia, parts of southern New South Wales, and areas in south-eastern Western Australia and the western Top End in the Northern Territory. Rainfall was very much above average (in the highest 10% of Decembers since 1900) for large parts of South Australia, Victoria and northern Queensland. December rainfall was the highest on record for parts of Queensland's North Tropical Coast and Tablelands district. Many stations in northern Queensland had their record highest December total rainfall.

Rainfall was below to much below average for large parts of western and northern Western Australia. Perth Metro and Perth Airport stations did not record any rainfall in December. Rainfall was also below to very much below average for large parts of the Northern Territory and north-western Queensland, and for an area of western New South Wales extending into eastern South Australia.

Significant weather and records

Wet start to the month in south-eastern states

A low pressure system that developed over New South Wales and moved eastwards close to the end of November, brought heavy rainfall to eastern Victoria at the beginning of December, where some stations had their highest December daily rainfall at the beginning of the month. The highest  rainfall total of 167.0 mm was recorded at Balook (Victoria) in the 24 hoursto 9 am on the 1st. Warm sea surface temperatures off the south-eastern Australian coast (in excess of 3 °C above average) provided additional moisture for this event, and a low pressure trough combined with a moist easterly airflow resulted in thunderstorms and showers on the 2nd and 3rd. Moderate to heavy rainfall and showers brought flooding to eastern Victoria and south-eastern New South Wales. Major flooding occurred along parts of the Avon and Thompson Rivers (Victoria), while minor to moderate flooding impacted many other rivers thtough eastern Victoria and south-eastern New South Wales.

Heatwave conditions across most of Australia

A heatwave that affected most of Australia between 2 and 10 December was caused by strong heating of a dry airmass over western and central parts of the mainland. The airmass then slowly moved into eastern parts of the country, with widespread above average daytime and night-time temperatures. Daytime temperatures peaked 10 to 15 °C above average through inland South Australia, New South Wales, southern Northern Territory and south-western Queensland, with maximum temperatures exceeding 40.0 °C in these areas. Some stations had their highest daily maximum temperatures on record for December, including Sydney Airport which has 85 years of data. Heatwave conditions began to ease from the 9th, contracting to northern parts of the country and New South Wales. Fire Danger Ratings were High to Extreme for parts of Western Australia, South Australia and New South Wales, reaching Catastrophic for parts of South Australia on the 8th, due to the hot, dry, windy conditions ahead of a cold front.

Severe to extreme heatwave conditions developed across much of northern Australia in the second half of the month, with daytime temperatures generally 5 to 10 degrees above average, and night-time temperatures also above average. Dry and windy conditions generated elevated fire danger through much of Western Australia and the Northern Territory. In the last week, heatwave conditions expanded to central Australia and most of Queensland. On the 29th, there were very warm conditions in south-eastern Queensland with Brisbane recording 38.3 °C. Several stations in northern Australia had their highest daily maximum temperature on record for December  on the last two days, although mostly stations with less than 30 years of observations. Roebourne Aero (Western Australia) had 49.5 °C on the 31st, which was the highest temperature recorded in Australia in 2023.

Heavy rainfall and low temperatures in South Australia

On 8 and 9 December, a cold front moved across south-eastern Australia. A low pressure system started to develop over eastern South Australia on the 10th, bringing widespread rainfall and thunderstorms to south-eastern South Australia, Victoria and south-eastern New South Wales. Persistent rainfall resulted in two-day rainfall totals to 9 am on the 11th of 50 to 100 mm, and locally above 100 mm, at many stations across the Eyre Peninsula and south-eastern South Australia. These areas are typically drier at this time of the year, with average December rainfall generally less than 50 mm. Many stations had their highest daily rainfall record for December.

Cold air that followed the front resulted in daily maximum temperatures 8 to 14 °C below average in parts of Western Australia, South Australia and southern Northern Territory, with daily maximum temperatures in high teens or low 20s. Some sites in South Australia had their lowest daily maximum temperature on record for December on the 9th and 10th.

Tropical Cyclone Jasper

Tropical Cyclone Jasper (the first tropical cyclone in the 2023–2024 season in the Australian Area of Responsibilty) formed on 5 December from a tropical low near the Solomon Islands. It quickly intensified and reached a Severe Tropical Cyclone strength (Category 3) on the 6th while moving south-westwards towards the Coral Sea. Tropical Cyclone Jasper intensified further reaching its peak intensity (Category 4) on the 8th, but subsequently weakened to Category 2. Its outer rainbands started affecting Queensland's North Topical Coast on the 12th, and its core crossed the coast around 9 pm on the 13th in the vicinity of Cape Tribulation (near the indigenous community Wujal Wujal), south of Cooktown. After landfall, it was downgraded to a tropical low. Ex-Tropical Cyclone Jasper brought to Northern Queensland damaging winds, intense rainfall, flooding and storm surge. Over 40,000 people were without power and there were many reports of downed trees, from Port Douglas to Daintree Village.

Persistent rainfall continued as ex-Tropical Cyclone Jasper very slowly moved across Northern Queensland over the several days. Due to its slow movement, high daily rainfall totals were recorded across a wide area between Cooktown and Cardwell. A number of stations in the region had their highest daily precipitation on record for December. This heavy rainfall resulted in flash flooding, landslides, road closures and riverine flooding across Daintree, Mossman, Barron, Murray, Mulgrave and Herbert Rivers. On the 18th, Daintree River at Daintree Village reached 14.85 m, well above the major flood level of 9m, and above the old flood record of 12.6 m from 2019. At Cairns Airport, the Barron River was estimated (the gauge was not available) at 4.4 m, exceeding the 1977 flood level of 3.8 m.

Multiple sites in Northern Queensland observed 5-day rainfall accumulations (14 to 18 December) in excess of 1000 mm. The highest 5-day total (at the Bureau's station) of 1933.8 mm was recorded at Whyanbeel Valley station. The highest daily rainfall total during this event of 714.0 mm was recorded at Mossman South Alchera Drive in the 24 hours to 9 am on the 18th (Australia's highest December rainfall total). Several non-Bureau sites recorded 5-day rainfall totals of more than 2000 mm.

By the 19th, the system weakened and shifted northward, with heavy rainfall easing.

Thunderstorms in eastern and south-eastrn Australia

Low pressure troughs brought intense thunderstorm activity with damaging wind gusts and heavy rainfall to parts of eastern Queensland and New South Wales between 2 and 4 December. A severe thunderstorm passed across Sydney late on the 2nd resulting in fallen trees and property damage. In the afternoon on the 4th, severe thunderstorms moved across the Sunshine Coast bringing giant hail, gusty winds and heavy rainfall. Gympie and Maryborough, in the south-east of the state, reported hail with some hailstones around 10 cm in diameter (hailstones with diameter greater than 5 cm are classified as giant hail) and wind gusts in Maryborough exceeded 85 km/h resulting in fallen trees.

On the 15th, a cluster of severe thunderstorms brought destructive wind gusts and intense rainfall to southeastern Queensland including Brisbane, and north-eastern New South Wales. Daily rainfall totals to 9 am on the 16th exceeded 100 mm in parts of the Brisbane and Sunshine Coast area, with most of the rain falling in a short period of time. A wind gust of 169 km/h was recorded at the Archerfield Airport (Queensland), an annual highest daily wind gust for this station which has 35 years of data. Extensive damage was reported, with numerous fallen trees that damaged powerlines leaving 35,000 customers without power. 

A low pressure trough over western Queensland and New South Wales brought daily thunderstorms to eastern and south-eastern Australia on most days between 19 and 26 December.  Severe thunderstorms brought giant hail, well in excess of 5 cm, to Gatton (Queensland) on the 23rd and Burpengary on the 24th. A slow-moving severe thunderstorm delivered 91.2 mm of rainfall to Sydney Airport on the 24th causing flooding and flight delays. Severe thunderstorms brought more hail on the 25th to some areas in New South Wales and south-eastern Queensland. In Orange (New South Wales), large hail was so extensive that it made the ground look like it was covered with snow, while in south-eastern Queensland 130,000 customers were left without power due to strong winds. The strongest wind gust at a Bureau station was 106 km/h at the Gold Coast Seaway (Queensland), although thunderstorms may have caused even stronger localised areas of damaging or destructive winds. A tornado moved across parts of the Gold Coast and Scenic Rim (Queensland) in the evening on the 25th, leaving destruction in its path.

On the 24th a low pressure trough extended into Victoria and deepened, and a low pressure system developed over southern New South Wales and northern Victoria. This low pressure system brought strong and gusty winds and widespread showers to Victoria and southern New South Wales on 25 December. Much of Victoria had daily rainfall totals between 30 and 60 mm on this day with some stations in central and northern Victoria recording much higher daily rainfall totals, which led to areas of flooding and swift water rescues around Wedderburn and Kyneton in the morning on the 25th. In the 24 hours to 9 am on the 25th, some stations had their highest daily rainfall for December, including Kerang which has 144 years of data. The wettest area in New South Wales was the South Coast district which had persistent rainfall through much of the 25th; in the 24 hours to 9 am on the 26th, Moruya recorded 109.0 mm and Bemboka 101.0 mm.

The outbreak of thunderstorms continued on the 26th, with thunderstorms across central and eastern Victoria, eastern New South Wales and eastern Queensland. Heavy rainfall was observed around Hunter and Central Coast districts (New South Wales) and hail of about 5 cm in diameter was recorded near Richmond (New South Wales). More settled weather returned to eastern Australia from the 28th, but thunderstorms affected parts of New South Wales and Queensland on the last two days of the month. On the 30th, thunderstorms developed in areas north of Brisbane, with reports of flash flooding, large hail and damaging winds. The highest daily rainfall total recorded to 9 am on the 31st was 127.6 mm at Beerburrum (Queensland).

Rank ranges from 1 (lowest) to 124 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Departure from mean is relative to the long-term (1961–1990) average.