Australia in December 2021

In brief

• December rainfall was 6% below average for Australia as a whole
• Rainfall for December was below or very much below average across much of Western Australia, southern and eastern South Australia, western and southern Victoria, Tasmania, and parts of Central Australia and the inland north
• Rainfall was particularly low for Tasmania — sixth-driest December on record for Tasmania
• Rainfall was above average for the Top End of the Northern Territory and Cape York Peninsula in Queensland, much of eastern and parts of northern New South Wales, eastern Victoria, and some parts of Queensland's tropics
• Mean maximum temperatures for December were warmer or very much warmer than average for Western Australia, the Northern Territory, western Queensland and parts of Cape York Peninsula, north-western Victoria, and Tasmania; cooler than average for the south-eastern quarter of Queensland away from the coast, and parts of New South Wales in the North-West Slopes and Plains and the south coast
• Mean minimum temperatures for December were warmer than average for much of Western Australia, Central Australia, much of Queensland, and the Top End of the Northern Territory; cooler than average for small areas on the coast of South Australia and southern Western Australia, inland New South Wales, and pockets in the Northern Territory

Temperatures

The national mean temperature for December was 1.04 °C warmer than the 1961–1990 average for Australia as a whole, the equal-ninth-warmest December on record. The mean maximum temperature for December was 1.38 °C warmer than average, and the mean minimum temperature was 0.70 °C warmer than average.

Mean maximum temperatures for December were warmer or very much warmer than average for Western Australia, the Northern Territory, western Queensland and parts of Cape York Peninsula, north-western Victoria, and Tasmania. For Western Australia as a whole the mean maximum temperature was the third-warmest on record for December, and the fourth-warmest for the Northern Territory. Mean maximum temperatures for December were cooler than average for the south-eastern quarter of Queensland away from the coast, and parts of New South Wales in the North-West Slopes and Plains and the south coast.

Mean minimum temperatures for December were warmer than average for much of Western Australia, Central Australia, much of Queensland, and the Top End of the Northern Territory. For Western Australia as a whole the mean minimum temperature was the fourth-warmest on record for December. Mean minimum temperatures for December were cooler than average for small areas on the coast of South Australia and southern Western Australia, inland New South Wales, and pockets in the Northern Territory.

At the start of the month, Western Australia continued to experience heatwave conditions continuing from late November. The north of Western Australia experienced severe heatwave conditions a number of times during the month, with a number of sites in the Pilbara observing their hottest December days on record, while some sites had their warmest December nights on record.

Marble Bar recorded a total of 16 days with maximum temperatures at 45 °C or above in December, the highest count for December on record and the second-highest count for any month. Marble Bar also recorded 29 consecutive days of at least 42 °C, exceeding the site’s December record of 25 days in 1986. 

A severe to extreme heatwave affected the west coast of Western Australia in late December, with daytime and overnight temperatures peaking on Christmas Day (25th) and Boxing Day (26th). Several sites observed their highest December temperature on record or warmest December night on record. Some sites observed daily records for any time of the year. During the event Perth observed 4 consecutive days with maximum temperatures reaching 40 °C, a first for December (4 consecutive days also occurred in February 2016 & 1933).

Geraldton Airport recorded 6 consecutive days with maximum temperatures at 40 °C or above between the 24th and 29th, which was its longest such run in December and the equal second-longest run for any month at Geraldton (combining the current and old sites observations from 1941).

Conversely, in the Northern Territory a few sites around the Top End observed their coolest December day (lowest daily maximum temperature) on the 25th, associated with heavy rain.

Further discussion and tables of records for each state and the Northern Territory can be found in the individual regional climate summaries.

Rank ranges from 1 (lowest) to 112 (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

December rainfall was 6% below average for Australia as a whole.

Rainfall was below average for much of Western Australia, southern and eastern South Australia, western and southern Victoria, Tasmania, and parts of Central Australia and the inland north. For large parts of the southern coastline of the mainland and across most of Tasmania rainfall for the month was very much below average, decile 1 (the lowest 10% of historical observations).

Rainfall was above average for the Top End in the Northern Territory and Cape York Peninsula in Queensland; much of eastern New South Wales, extending into south-eastern Queensland and far eastern Victoria; and in some parts of upper western New South Wales to southern inland Queensland, and pockets of Queensland's tropics.

On the first day of the month, a surface trough generated widespread showers and thunderstorms over central to eastern Queensland, including some locally heavy falls in the south-east quarter of the state leading to some sites observing their highest December daily rainfall on record.

Another surface trough brought showers and rain to central and eastern parts of New South Wales a little later, with a number of sites recording daily rainfall totals to 9am on the 10th of 50 mm or more, including some daily rainfall records for December.

Severe winds affected broad areas of eastern Australia on the 19th as a cold front crossed south-eastern Australia, with gusts over 100 km/h recorded at a number of locations in Victoria, New South Wales, and Tasmania. In Sydney's northern beaches, the State Emergency Service received almost 600 requests for assistance, with damage to damage to trees and structures in reported across parts of New South Wales and Victoria.

A tropical low pressure system brought heavy rainfall to parts of the Northern Territory and Queensland late in the month, generating widespread moderate to locally heavy falls across the Top End for several days. Daily rainfall records for December were set at numerous sites in the Top End of the Northern Territory between the 25th and 28th. Extreme rainfall continued in northern Queensland until the end of the month, including 345 mm at Kowanyama over two days.

Further discussion and tables of records for each state and the Northern Territory can be found in the individual regional climate summaries.

Rank ranges from 1 (lowest) to 122 (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.