Australia in autumn 2011

In Brief

Autumn 2011 was the coldest on record for mean temperatures (average of maximum and minimum temperatures, records began in 1950) and the fourth wettest on record nationally. Daytime temperatures were particularly cool across most of Australia and ranked as the second coldest on record. The western half of Western Australia was drier and warmer than normal for both daytime and overnight temperatures.


Temperatures

Maximum temperatures averaged over Australia were 1.40°C below normal for autumn, resulting in the second coldest autumn on record (record is -1.46°C in 2000). Most of Australia recorded temperatures cooler than 1°C below the autumn average. Parts of the east Kimberley in Western Australia and the Northern Territory experienced their coldest autumn maximum temperatures on record (up to 4°C below average) with the Northern Territory as a whole experiencing its coldest autumn on record. Small parts of the interior of Western Australia and areas near the towns of Normanton, Clermont and Emerald in Queensland also recorded their coldest autumn on record. South Australia recorded its second coldest autumn maxima on record with Victoria recording its fourth coldest.

The cool conditions experienced in autumn 2011 are largely a result of the strong 2010/11 La Niña event which brought heavy rainfall and cool daytime temperatures to Australia, before decaying in late autumn. Of particular significance was March 2011 – Australia’s wettest and coldest March on record for maximum temperatures. It was also the third wettest month on record for any calendar month.

Nationally averaged minimum temperatures were 0.90°C below normal, with all states recording below their long-term average overnight temperatures, with Tasmania close to normal. Large areas of the Northern Territory, Queensland and western parts of Western Australia and southwest NSW recorded overnight temperatures 1°C below average with parts of the central Northern Territory and Queensland interior recording temperatures cooler than 2°C below normal.

In stark contrast, western parts of Western Australia recorded above average temperatures for both daytime and overnight temperatures. Maximum temperatures along the west coast were in excess of 2°C above the autumn average with some areas along the coast recording their warmest autumn on record for maximum temperatures. Most of the west coast experienced minimum temperatures up to 2°C above average which ranked in the top 10% of records.

For more information on Australia’s coldest autumn since at least 1950 please see Bureau’s Special Climate Statement number 33.


Areal average temperatures
  Maximum Temperature Minimum Temperature
Rank
(out of 62)
Anomaly*
(°C)
Comment Rank
(out of 62)
Anomaly*
(°C)
Comment
Australia 2 −1.40 Second lowest on record; Record −1.46 (2000) 5 −0.90 Lowest since 2001
Queensland 5 −1.23 Lowest since 1971 4 −1.31
New South Wales 10 −0.62 Lowest since 1995 15 −0.81
Victoria 4 −1.09 Lowest since 1995 equal 27 −0.49
Tasmania 34 +0.04 equal 35 −0.05
South Australia 2 −1.62 Second lowest; Record is −2.08 (1955) equal 25 −0.28 Lowest since 2001
Western Australia 6 −1.13 Lowest since 2000 16 −0.39
Northern Territory 1 −2.55 Lowest on record; previous record −2.11 (2000) 2 −1.94 Second lowest on record; Record −2.04 (1976)

*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

Australia experienced another wet season with autumn 2011 the fourth wettest autumn on record. Nationally averaged rainfall was 202.9 mm (68% above normal). Northern and central parts of Australia in particular recorded above average falls, with the Northern Territory recording its wettest autumn (334.7 mm, 140% above normal) beating the previous record in 1983 by 30 mm. Queensland, South Australia and Western Australia also recorded above average rainfall statewide with NSW, Victoria and Tasmania all recording near-normal rainfall.

The above average falls during autumn were strongly influenced by the wet conditions in March 2011, where Australia recorded rainfall 141% above the March average. March 2011 ranked as Australia’s wettest March on record and the third wettest month (of any calendar month) on record. April was also above average (by 18%); however, with the decay of the 2010/11 La Niña the influence on Australia’s rainfall dropped off with below average rainfall recorded in May (46% below normal). It was the wettest autumn on record for the Northern Territory, and ranked seventh in Queensland and tenth in South Australia. Areas that recorded well above average autumn rainfall include large parts of northern and central Australia, while the western areas of Western Australia as well as western Tasmania and other scattered areas in Australia had well below average rainfall (see maps below).


Areal average rainfall
Rank
(out of 112)
Average
(mm)
Departure
from mean*
Comment
Australia 109 202.8 +68.3% Highest since 2000
Queensland 106 280.9 +72% Highest since 1990
New South Wales 77 136.1 −5%
Victoria 67 151.1 −4%
Tasmania 35 304.3 −11%
South Australia 103 94.2 +67% Highest since 1989
Western Australia 102 146.5 +62%
Northern Territory 112 334.7 +140% Highest on record; previous record 304.8 (1983)
Murray-Darling Basin 84 122.3 +3%

*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 2011
Hottest day 41.1 °C at Roebourne (WA) on the 19th March
Coldest day −4.6 °C at Thredbo (NSW) on the 11th May
Coldest night −9.0 °C at Woolbrook (NSW) on the 15th
Warmest night 30.0 °C at Bedout Island (WA) on the 14th March
Wettest day 477.2 mm at Mornington Island (QLD) on the 1st 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 Wednesday 1 June 2011. 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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