Australia in December 2013

In Brief

December was another warm month for Australia, with above-average maximum and minimum temperatures recorded across much of the eastern and southern mainland. The national maximum temperature anomaly, +0.77 °C, and minimum temperature anomaly, +0.40 °C, combined to give a mean temperature anomaly of +0.58 °C. Maxima were near-average for Tasmania and below average for much of northwestern and northern Western Australia. Minima were below average for the east coast of Queensland and isolated areas of the north but above average for most of Western Australia, excluding the Kimberley and southwest, central South Australia, western Queensland and adjacent parts of the Northern Territory and in East Gippsland and southeastern New South Wales.

Rainfall was below the long-term average when averaged nationally (23% below average). Rainfall was very much below average for much of eastern and central Queensland and northeastern New South Wales, with drier-than-average conditions generally observed from the eastern Top End through to New South Wales. Above-average monthly rainfall was most widespread in northwestern Western Australia, adjacent parts of the northwest of the Northern Territory and southeastern Western Australia. Rainfall for the southwest of Western Australia and western Victoria was generally lower than average.


Temperatures

December was the seventeenth consecutive month in which Australia recorded an above average mean temperature, and concluded with a heatwave and record-breaking warmth across parts of the eastern interior (a Special Climate Statement to be released shortly will discuss this event). The national area-averaged maximum temperature anomaly was +0.77 °C, the minimum temperature anomaly was +0.40 °C and the mean temperature anomaly was +0.58 °C.

The Northern Territory was the only region to record below-average temperatures for either maxima or minima (minimum temperatures 0.47 °C below average). Maximum temperatures for Queensland, New South Wales, Victoria and South Australia ranged from 1.31 °C warmer than average to 1.64 °C warmer than average, although none made it into the top ten warmest Decembers for that State. Maximum temperatures were above to very much above average across the southern mainland, extending through southern and inland Queensland to the Gulf of Carpentaria. The Top End and the tip of Queensland's Cape York Peninsula also recorded above average maxima. Days were cooler than average in an area covering most of the Kimberley and adjacent western edge of the Victoria River District of the Northern Territory, the north of Western Australia's Interior District and the western Pilbara. Maxima were in the highest 10% of records in a large part of Western Queensland, on the coast north of the Great Australian Bight and an area along the west coast of Western Australia.

Area-averaged minima were above average for western Queensland and adjacent parts of the Northern Territory, southwestern and central South Australia, most of Western Australia south of the Kimberley except for the southwest, as well as for smaller areas in southwestern New South Wales, southeastern New South Wales and eastern Victoria and both northwest and southeast Tasmania. Cooler-than-average nights were recorded along the east coast between northeastern New South Wales and central Queensland as well as in small areas in the Kimberley, the north of the Northern Territory and around and inland of Cairns in northern Queensland.


Areal average temperatures
Maximum Temperature Minimum Temperature Mean Temperature
Rank
(of 104)
Anomaly
(°C)
Comment Rank
(of 104)
Anomaly
(°C)
Comment Rank
(of 104)
Anomaly
(°C)
Comment
Australia 90 +0.77 = 82 +0.40 89 +0.58
Queensland 91 +1.31 76 +0.50 87 +0.90
New South Wales 86 +1.64 73 +0.49 = 83 +1.07
Victoria 90 +1.60 73 +0.59 86 +1.10
Tasmania = 71 +0.67 = 59 +0.16 = 71 +0.41
South Australia 93 +1.55 75 +0.73 91 +1.14
Western Australia = 76 +0.37 80 +0.27 81 +0.32
Northern Territory = 49 −0.47 = 62 +0.15 54 −0.16

Rank ranges from 1 (lowest) to 104 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Anomaly is the departure from the long-term (1961–1990) average.


Temperature maps
MeanAnomalyDeciles
Mean
daily
maximum
temperatures
Map of mean daily maximum temperature Map of mean daily maximum temperature anomalies Map of mean daily maximum temperature deciles
Mean
daily
minimum
temperatures
Map of mean daily minimum temperature Map of mean daily minimum temperature anomalies Map of mean daily minimum temperature deciles
Mean
daily
temperatures
Map of mean daily temperature Map of mean daily temperature anomalies Map of mean daily temperature deciles

Rainfall

Nationally-averaged rainfall during December was 23% below the long-term average. Western Australia was the only State to record above-average monthly rainfall (+56%) while Queensland and New South Wales recorded the largest negative anomalies (−68% and −57% respectively). Rainfall was also significantly below average across the Murray–Darling Basin (−57%), reflecting the drier-than-average month in those States. For Queensland, the area-averaged total of 26.2 mm was the third-lowest December rainfall on record.

December rainfall was below to very much below average across much of eastern Australia, extending from the eastern Top End through Queensland and most of New South Wales. A large area of inland central and southern Queensland received less than 10 mm for the month, contributing to ongoing rainfall deficiencies in this region. Areas of western Victoria, southeastern Tasmania and the South West Land Division of Western Australia also recorded below-average rainfall while much of the remainder of Western Australia and adjacent parts of the Victoria River District of the Northern Territory recorded above-average rainfall for the month, partly associated with the passage of severe tropical cyclone Christine during the last week of December. Other smaller areas of above-average rainfall were also recorded in parts of central Australia and along the western half of the New South Wales–Victoria border.


Area-average rainfall
Rank
(of 114)
Average
(mm)
Departure
from mean
Comment
Australia 28 40.1 −23%
Queensland 3 26.2 −68% 3rd lowest (record 19.6 mm in 1938)
New South Wales 15 23.0 −57%
Victoria 53 38.3 −19%
Tasmania 50 89.0 −15%
South Australia 70 16.7 −9%
Western Australia 88 49.7 +56%
Northern Territory 49 66.6 −10%
Murray-Darling Basin 14 21.1 −57%

Rank ranges from 1 (lowest) to 114 (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.


Rainfall maps
TotalsPercentagesDeciles
Total
rainfall
Map of total rainfall Map of percentage of normal rain Map of rainfall deciles


Australian weather extremes during December 2013
Hottest day   47.4 °C at Eucla (WA) on 5 December
Coldest day     0.0 °C at Mount Hotham (Vic.) on 5 December
Coldest night   −4.6 °C at Thredbo AWS (NSW) on 6 December
Warmest night   32.6 °C at Arkaroola (SA) on 21 December
Wettest day 167.6 mm at Wyndham Aero (WA) on 23 December


Notes

The Monthly Climate Summary is prepared to list the main features of the weather in Australia using the most timely and accurate information available on the date of publication; it will generally not be updated.

This statement has been prepared based on information available at 12 noon EST on Wednesday 1 January 2013. Some checks have been made on the data, but it is possible that results will change as new information becomes available, especially for rainfall where much more data becomes available as returns are received from volunteers.

Long-term averages in this statement and associated tables are for the period 1961 to 1990 unless otherwise specified.

In the tables, fractional ranks denote tied values.

A new area-averaging method was adopted for rainfall in May 2009. Current and historical totals for Tasmania are substantially higher than under the old scheme, but differences for other states, and nationally, are negligible. The rankings and departures from mean shown here use the new method.

The ACORN-SAT temperature dataset has been used for calculation of state and national temperature area averages in summaries from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.


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