Australia in autumn 2012

In Brief

Autumn 2012 was a period of transition, beginning with La Niña in place over the tropical Pacific Ocean, and shifting to neutral conditions by the end. Rainfall was generally above average across northern and eastern parts of the country, with the southwest a notable exception.

Temperatures were generally below average, with the exception of Tasmania and the southwest daytime temperatures.


Temperatures

Autumn maximum temperatures across the nation were generally close to normal, with parts of northern Australia notably cooler than normal, and much of the southern half of WA warmer than normal. For Australia as a whole, autumn maximum temperatures were 0.37°C below normal and 17th coolest of 63 years. The NT experienced its 8th coolest autumn daytime temperatures, with an anomaly of −1.11°C.

Maximum temperatures more than 1°C below normal were measured in the eastern Kimberley of WA, much of the central region of the NT, and parts of northern inland Queensland. Some of this area was in the coolest 10% of records (first decile). Parts of northeast Victoria and adjacent southern inland NSW also recorded daytime temperatures more than 1°C below normal. Conversely, further west much of the WA western coastline was more than 1°C above average, as was the Nullarbor near the WA-SA border. Much of this area was in the highest decile, with an area around Carnarvon and Shark Bay on the WA coast measuring its warmest autumn daytime temperatures on record.

Minimum temperatures for autumn were below average across most of mainland Australia, except for parts of the coastal fringe, mainly in the south and far north. Nationally averaged overnight temperatures were 0.93°C below normal, the 4th coolest autumn out of 63 years, and the coldest since 1994. State-wise, WA received its 5th lowest autumn minima, with an anomaly of −0.86°C, while the NT and NSW each ranked 6th (−1.26°C and −1.31°C, respectively), and SA 10th. In contrast to the mainland, Tasmania was the only State to record above average overnight temperatures, recording its 4th warmest autumn minima.

Anomalies below −1°C were measured over much of the eastern mainland, away from the coast, as well as areas in northern and central WA, and in central Australia (see map below). Parts of this area were in decile 1, namely, parts of the Kimberley in WA, an area near the SA-NT-WA border intersection, eastern SA and central NSW. Southern and western Tasmania by comparison, recorded minima in decile 10 (warmest 10% of records).


Areal average temperatures
  Maximum Temperature Minimum Temperature
Rank
(out of 63)
Anomaly*
(°C)
Comment Rank
(out of 63)
Anomaly*
(°C)
Comment
Australia 16.5 −0.37 4 −0.93 lowest since 1994
Queensland 13 −0.64 13 −0.84
New South Wales 17.5 −0.33 6.5 −1.31
Victoria 28 −0.11 27 −0.50
Tasmania 49 +0.46 60 +0.98 4th highest
South Australia 30 +0.03 9.5 −0.70 lowest since 1995
Western Australia 30 −0.02 5 −0.86 lowest since 2000
Northern Territory 8 −1.11 6 −1.26

*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

Rainfall

Rainfall for autumn 2012 was generally above average across the northern and eastern parts of the country, with much of this a result of the heavy falls received during March. The autumn period began with La Niña conditions in place over the Pacific Ocean, and as is typical during La Ninña events, the tropical Pacific Ocean progressed to neutral conditions over the course of autumn.

For Australia as a whole, the area-averaged rainfall was 150.9 mm (25% above normal), and ranked as the 18th wettest autumn of 113 years. All States and Territories, except for WA, received above average falls. While no State or Territory recorded rainfall in the top/bottom 10 of records, southwest WA (southwest of a line joining Jurien Bay and Bremer Bay) received its 7th lowest autumn rainfall. Tasmania experienced its wettest autumn since 1977, and Victoria since 1989.

Rainfall was generally above average north of a line joining Rockhampton in Queensland, Alice Springs in the NT and Port Hedland in WA. Other areas of above average falls included eastern SA, and a band from southwest Queensland reaching down through most of NSW (except the northeast) to eastern Victoria and Tasmania. Highest on record falls were measured in isolated areas across the northern tropics, including a larger area at the western base of the Cape York Peninsula in Queensland, as well as locally in southern NSW and far northeast SA. The above-average falls in inland NSW and northeast Victoria, where it was widely the wettest autumn since 1989, were largely the result of a single major rain event at the start of March, with rainfall then near or below normal for the remainder of the season.

Rainfall was below normal over large parts of western WA from Karratha southwards and was in the lowest decile in most of the southwest. Record low autumn falls occurred locally around Jurien Bay and north of Albany. Rainfall was also below normal in some eastern border areas of WA, in parts of northeast NSW and the Darling Downs of Queensland, and locally in far southwest Victoria.

During autumn, two tropical cyclones were recorded in the Australian region in early March, Tropical Cyclone Koji-Joni and Severe Tropical Cyclone Lua. Lua made landfall over the WA Pilbara coastline near Pardoo as a category 4 cyclone, making it the strongest cyclone to hit the Australian coast since Yasi in 2011. Lua caused significant damage from strong winds, and moderate to major flooding was reported.


Areal average rainfall
Rank
(out of 113)
Average
(mm)
Departure
from mean*
Comment
Australia 96 150.9 +25%
Queensland 100 240.5 +47%
New South Wales 92 166.1 +16% highest since 2000
Victoria 89 183.9 +17% highest since 1989
Tasmania 87 395.6 +16% highest since 1977
South Australia 79 57.0 +1%
Western Australia 55 88.6 −2%
Northern Territory 95 194.7 +40%
Murray-Darling Basin 87 133.5 +12%

*The mean is calculated for the 1961-1990 reference period.


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


Australian weather extremes in autumn 2012
Hottest day 44.6 °C at Kalbarri (WA) on the 9th March
Coldest day −3.1 °C at Thredbo (NSW) on the 25th May
Coldest night −10.0 °C at Charlotte Pass (NSW) on the 30th May
Warmest night 29.9 °C at Thevenard Island (WA) on the 10th March
Wettest day 388.0 mm at Mount Jukes (Qld) on the 21st March


Notes

The Seasonal 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 2pm EST on Friday 1 June 2012. 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.


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