Thursday, 1 September, 2011 — Seasonal Climate Summary for Australia — Product Code IDCKGC1A00
Rainfall across Australia in winter 2011 was below normal with much of southeastern Australia away from the east coast recording below normal falls. Parts of the east coast recorded very much above average rainfall due to a recurring series of low pressure and cold fronts affecting the area. Day time temperatures were above normal across large parts of Australia with the exception of the tropical north. Overnight minima were above average in the parts of southern and western Australia, while the tropical north experienced generally below average temperatures.
Maximum temperatures averaged over Australia were 0.69°C above normal for winter. Large areas of the southern mainland recorded maximum temperatures 1 to 2°C above the winter average. Large areas of NSW, South Australia, Tasmania and Victoria recorded daytime temperatures which ranked in the warmest 10% of records, with Tasmania and Victoria recording their second warmest winters on record, and NSW its third. The warm conditions in these areas were partly associated with the drier than normal conditions during the period. Areas on both sides of the Murray River in north-central Victoria and the NSW Riverina had their warmest winter maxima on record. Areas in the interior of the Northern Territory and parts of northern Queensland recorded below average maximum temperatures. Parts of the east coast of Australia also recorded below average temperatures, which were partly associated with the above average rainfall in those areas.
Nationally averaged minimum temperatures were 0.20°C below normal, with a distinct contrast recorded between the tropical north and the western and southern parts of Australia. Night time temperatures up to 3°C below the winter average were recorded across the tropical north, with June being especially cool. The north Kimberley, large parts of the Northern Territory and parts of Queensland recorded minimum temperatures which ranked in the coolest 10% of records. Two small areas, one surrounding Wyndham in Western Australia and the other near Elliott in the Northern Territory, had minimum temperatures up to 3°C below average, resulting in their coldest winter minimum temperatures on record. The Northern Territory recorded its fifth coldest winter on record.
In contrast most of the southwestern half of Western Australia as well as southwest South Australia recorded minimum temperatures in excess of 1°C above normal, which ranked in the top 10% of warmest winters on record. Large parts of the WA Goldfields and Nullarbor recorded their warmest winter nights on record. The warm overnight temperatures were partly associated with above average rainfall in these areas. Parts of southern Victoria and most of Tasmania recorded overnight minima ranking in the warmest 10% of records, with Tasmania as a whole recording its fifth warmest winter for minimum temperatures and third warmest for mean temperatures.
|Areal average temperatures|
|Maximum Temperature||Minimum Temperature|
(out of 62)
(out of 62)
|Queensland||36||+0.37||equal 9||−0.99||Lowest since 1982|
|New South Wales||60||+1.33||Third highest; Record is +1.96 (2002)||equal 34||+0.24|
|Victoria||61||+1.24||Second highest; Record is +1.29 (2005)||43||+0.36|
|Tasmania||61||+1.23||Second highest; Record is +1.32 (1988); highest since 1988||58||+0.95|
*Anomaly is the departure from the long-term (1961-1990) average.
Australia has experienced its first drier than normal season since the spring of 2009, with a nationally averaged rainfall total of 56.3 mm (12% below normal). Well above average rainfall was recorded along the northern half of the NSW coast, an area in the east Gippsland region of Victoria and parts of the east coast of Tasmania. These areas recorded above to well above average rainfall in June, July and August with several strong cold fronts and complex low pressure systems producing significant falls and flooding in these areas throughout winter 2011. An area in Western Australia stretching from Carnarvon on the west Gascoyne coast across to the southeast coast near Eucla (see rainfall deciles map below) also recorded above to well above average rainfall which was mostly due to the falls recorded in these areas during June and July.
Most states, with the exception of Tasmania, recorded below normal rainfall for winter. The Murray-Darling Basin (MDB) recorded 74.0 mm for winter (33% below normal) with Queensland, the NT and South Australia also recording totals more than 20% below normal. Most of NSW and large parts of Victoria west of the Great Dividing Range recorded below normal rainfall.
Long term drying trends have been observed in the last 15 years in south-eastern Australia, particularly the central and lower Murray Darling Basin, Victoria and parts of South Australia. Rainfall declines in these regions have been largest in autumn and early winter. The strong La Niña conditions experienced in 2010 and 2011 dramatically punctuated long term rainfall deficiencies with above average autumn and winter rainfall in 2010 and record falls in the spring and summer of 2010/2011.
In light of the longer deficiencies, there has been some interest as to what level of rainfall will return after the demise of La Niña. After around six consecutive seasons of above average rainfall for the south-east, the region has returned to below average rather than average rainfall, with the emergence of rainfall deficits closely timed to the decay of La Niña in mid autumn. The rainfall deficits have been most pronounced north and west of the Divide in the Murray Darling Basin. Other areas of below average falls included eastern and southern parts of South Australia and parts of the south coast and southwest of Western Australia. Conditions were seasonally dry through most of the tropical north, with most tropical areas away from the east coast receiving less than 10 millimetres for the season.
|Areal average rainfall|
(out of 112)
|New South Wales||35||98.3||−15%|
*The mean is calculated for the 1961-1990 reference period.
|Australian weather extremes in winter 2011|
|Hottest day||37.5 °C at Noonamah (NT) on the 30th August|
|Coldest day||−4.1 °C at Mt Hotham (VIC) on the 7th June|
|Coldest night||−16.0 °C at Charlotte Pass (NSW) on the 27th July|
|Warmest night||25.5 °C at Coconut Island (QLD) on the 7th June|
|Wettest day||250.0 mm at Woolgoolga (NSW) on the 14th June|
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 Thursday 1 September 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.