Australia in Summer (December-February) 2010-11

In Brief

Summer 2010-11 has been the second wettest on record for Australia with Victoria recording its wettest summer on record, WA recording its second wettest, SA recording its third wettest and NSW recording its fifth wettest summer on record. Maximum temperatures were generally cooler than normal whilst overnight minima were mostly above normal, with SA recording its fourth warmest summer on record for minimum temperatures.

Significant rainfall and flooding occurred over large parts of eastern and northern Australia, most notably the southeast Queensland floods in early January 2011.


Temperatures

Maximum temperatures averaged over Australia were 0.72ºC below normal for summer making it the coolest year since 2001. Most of Australia recorded below average maximum temperatures. Daytime temperatures were more than 1ºC below normal in northeast and southern WA, a large part of NT and Queensland as well as in an area in southeast Australia. The northwest coast of WA also recorded maximum temperatures more than 1ºC below normal. Northern Territory and Queensland recorded the most pronounced cool anomalies of more than 2ºC below normal. This area, as well as an area in northern Queensland and parts of WA, ranked in the coolest 10% of records. The cool conditions in the NT and Queensland resulted in the coolest summer in a decade with anomalies of -1.40ºC and -0.97ºC recorded respectively in each state.

In contrast, areas in southwest Queensland, on the NSW central coast and over the eastern interior and west coast of WA, recorded maximum temperatures of over 1ºC above normal. Temperatures along the western coast of WA ranked in the top 10% of warmest summers on record, with records set locally in the far southwest and around Shark Bay.

Nationally averaged minimum temperatures were 0.49ºC above normal with most states recording above average minimums, with the exception of the NT. The southern half of the country recorded particularly above average overnight minima. This includes large areas in the interior and west coast of WA and large parts of SA, as well as the coast and tablelands of eastern NSW and far eastern Victoria, which all ranked in the warmest 10% of summers on record. The west coast of WA between Perth and Karratha recorded its warmest minimum temperatures on record, with temperatures more than 3ºC above normal, while South Australia recorded its fourth warmest summer on record statewide for minimum temperatures (+1.44ºC).

Parts of northeast WA and the inland NT recorded minimum temperatures of around 1ºC below normal which rank in the coolest 10% of summers on record. Most of the NT and northeast WA, as well as a large area of inland Queensland, recorded temperatures up to 1ºC below normal, with the rest of the state recording above average overnight minima.


Areal average temperatures
  Maximum Temperature Minimum Temperature
Rank
(out of 61)
Anomaly*
(°C)
Comment Rank
(out of 61)
Anomaly*
(°C)
Comment
Australia 8 −0.72   49 +0.49
Queensland 11 −0.97   32 +0.06
New South Wales 22 −0.32   48 +0.86
Victoria 14 −0.76 56 +1.20
Tasmania 27 +0.02 42 +0.22
South Australia 30 +0.10   58 +1.44 4th highest on record
Western Australia 12 −0.66 56 +0.70
Northern Territory 6 −1.40   14 −0.40 Lowest since 1983

*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 a very wet summer with all states and territories recording above average falls. Nationally averaged rainfall was 354.7 mm (70% above normal) which is second only to the summer of 1973-74 when 419.8 mm was recorded. Victoria recorded its wettest summer on record with a statewide average of 336.1 mm (181% above normal). WA had its second wettest summer on records with 290.9 mm (95% above mean), and SA having its third wettest summer on record with 159.9 mm recorded (158%above mean). NSW also recorded its fifth wettest summer on record with 273.2 mm (60% above mean).

Areas of very much above average rainfall were widespread across Australia, with the southern half of Australia having a particularly wet summer with only a few small areas recording below average rainfall. Most of Victoria, southern NSW, eastern SA, and parts of WA, as well as small areas in northern Australia and southeast Queensland, had falls which ranked as the highest on record. The wet conditions during summer resulted in major flooding in many areas across the country including Queensland, parts of NSW, Victoria and northern Tasmania.

One of the strongest La Niña events on record has driven the above average falls across much of the country. Tropical Cyclone activity has been above average in the Australian region which is typical during a La Niña event. This summer, a number of tropical cyclones resulted in heavy rainfall, flooding, and damage across the tropical north. Most notably this includes Tropical Cyclone Yasi which crossed the coast between the regional centres of Townsville and Cairns as a category 5 cyclone. Other tropical cyclones in the Australian region which were associated with significant rainfalls include Tropical Cyclone Tasha, Vince, Anthony, Bianca, and Carlos, although none caused major wind damage. A total of 10 tropical cyclones have occurred in the Australian region so far this season, already near the long-term seasonal average with two months still remaining in the main cyclone season.

Exceptional rainfall conditions also affected four of Australia’s capital cities: Darwin, which broke its record for wettest day, week and month in February with a monthly total of 1110.2 mm; Brisbane which experienced very heavy falls which led to severe flooding in early January; Canberra which recorded its second wettest summer on record; and Melbourne, which experienced exceptionally heavy rainfall in early February which resulted in flash flooding in the greater metropolitan area. For more information on these events please see the Bureau’s Special Climate Statement page.


Areal average rainfall
Rank
(out of 111)
Average
(mm)
Departure
from mean*
Comment
Australia 110 354.7 +70%

2nd highest on record; record is 419.8 (1973/1974)

Queensland 106 509.4 +57%  
New South Wales 107 273.2 +60% 5th highest on record; record is 384.9 (1975/1976)
Victoria 111 336.1 +181%

Highest on record; previous record 237.4 (1911)

Tasmania 95 338.9 +39% Highest since 1995/1996
South Australia 109 159.9 +158% 3rd highest on record; record is 195.9 (1973/1974)
Western Australia 110 290.9 +95% 2nd highest on record; record is 301.8 (1999/2000)
Northern Territory 104 473.5 +50%  
Murray-Darling Basin 109 271.9 +88% 3rd ighest on record; record is 336.1 (1975/1976)

*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 summer 2010-11
Hottest day 48.5 °C at Roxby Downs (SA) on 25 January
Coldest day 1.2 °C at Mt Hotham (Vic) on 19 December
Coldest night −14.1 °C at Trangie (NSW) on 6 February
Warmest night 34.2 °C at Oodnadatta (SA) on 28 January
Wettest day 435.4 mm at Marrara (NT) on 16 February


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 12 pm on Tuesday 1 March 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.


Further information

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