Australia in Summer (December-February) 2009-10

In Brief

The summer of 2009-10 was a rather wet one for most of Australia, particularly in the east, continuing a sequence in which eight of the last eleven summers have ranked in the wettest 20 of the last 110 years. It was also a warmer-than-normal summer, which combined with the extremely warm winter and spring to leave Australia with its warmest nine months on record. The heat was most concentrated in Western Australia, which had its hottest summer on record, but the southeast was also warmer than normal.


Temperatures

Maximum temperatures for the summer across Australia were 0.55°C above normal (11th highest on record). They ranked equal highest on record for Western Australia (where they contributed to mean temperatures being the highest on record, 1.32°C above normal) and second for Tasmania, and sixth-highest for Victoria.

Days were hotter than normal throughout Western Australia (except locally on the coast around Carnarvon and Onslow), Tasmania, Victoria, South Australia (except the far north), and New South Wales away from the far northwest. The strongest anomalies were in Western Australia. Most of the southern half of the state was at least 2°C above normal, reaching 3-4°C above normal in the Meekatharra-Newman area. Records were set over most of the wheatbelt and adjacent areas further inland, extending north to Shark Bay, east to Norseman, and west to coastal areas between Perth and Geraldton. Most remaining parts of the state, except some coastal areas and the north Kimberley, were 1-2°C above normal. Similar anomalies occurred throughout Tasmania, Victoria, the southern halves of New South Wales and South Australia, and the east coast extending north to southeast Queensland. Most of Victoria, Tasmania and southern South Australia were in the highest decile.

Below-normal maximum temperatures were found in Australia’s northeast and the eastern interior, including the bulk of Queensland and the Northern Territory. Anomalies were mostly small, although temperatures were 1°C or more below average in southwest Queensland and the southeastern Northern Territory, reaching 2°C below normal around Longreach.

Minimum temperatures were 0.76°C above normal, the fifth-highest on record, with Western Australia (anomaly +1.12°C) having its hottest summer nights on record. Almost all of the continent had above-normal minima, the only major exceptions being the far southwest of Queensland around Birdsville and Boulia, adjacent areas of the central Northern Territory, and the far southwest of Western Australia.

Most of interior Western Australia and the Nullarbor had nights 1-2°C above normal, with extensive areas throughout the region where seasonal records were set. Similar anomalies also occurred over most of New South Wales (except the far northwest and northeast), eastern and northern Victoria, and northeastern Tasmania. Most areas within 300 kilometres of the east coast from Gladstone southwards, as well as areas further west in southern New South Wales, had minimum temperatures in the highest decile, with records set in places on the NSW south coast. Minimum temperatures were also in the highest decile over large parts of the northern tropics.


Areal average temperatures
  Maximum Temperature Minimum Temperature
Rank
(out of 60)
Anomaly*
(°C)
Comment Rank
(out of 60)
Anomaly*
(°C)
Comment
Australia 50 +0.55 56 +0.76
Queensland 22 −0.57 39 +0.30
New South Wales 46 +0.94 52 +1.15
Victoria 55+1.54 53 +1.18
Tasmania 59 +1.96 2nd highest; record is +2.00 (1960-61) 32 +0.09
South Australia 44 +0.75 50 +1.05
Western Australia 59= +1.52 Equals record set in 1997-98 60 +1.12 Highest on record; previous record +0.80 (1972-73 and 1977-78)
Northern Territory 19 −0.44 32 +0.16

*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

Nationally averaged rainfall was 24% above normal (14th highest on record), with falls 30-50% above normal over New South Wales, Queensland, South Australia and the Northern Territory. The bulk of all four regions had above-normal rainfall, except for southern agricultural areas of South Australia, parts of eastern Arnhem Land (NT), parts of southeast Queensland (especially the Darling Downs) and northeastern New South Wales, and some of the Cape York Peninsula. The above-normal rainfalls also extended to northern and eastern Victoria, parts of that state’s southwest, and a few patches in the Kimberley and Great Sandy Desert of Western Australia, coinciding with the track of tropical cyclone Laurence in December.

Summer rainfalls were in the highest decile (wettest 10% of all years) over most of the southern Northern Territory, adjacent areas of northeast South Australia, and most of southern inland Queensland west of the Darling Downs (with records locally around Longreach). Falls in the highest decile also extended in a band through central New South Wales running from Walgett to Canberra, and to parts of that state’s south coast. Further north, they occurred locally in Western Australia on the Laurence track, in parts of the NT Top End (especially around and east of Darwin), and in northwest Queensland.

The most significant dry conditions were in Western Australia and Tasmania. Most of the west coast between Geraldton and Albany was in the lowest decile with records set around Perth. Perth Airport was one of a number of places where no rain was recorded during the summer, and is experiencing a record 101-day dry spell. Rainfall totals were also in the lowest decile on the north coast of Tasmania, and in the state’s southwest.


Areal average rainfall
Rank
(out of 110)
Average
(mm)
Departure
from mean*
Comment
Australia 97 258.3 +24%
Queensland 101 446.0 +37%
New South Wales 96 231.1 +38%
Victoria 70 129.6 +9%
Tasmania 18 178.1 −30%
South Australia 94 79.2 +31%
Western Australia 59 123.4 −17%
Northern Territory 99 446.2 +42%
Murray-Darling Basin 98 208.7 +48%

*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 2009-10
Hottest day 49.1 °C at Emu Creek (WA) on 2 January
Coldest day 3.5 °C at Mount Buller (Vic) on 18 January
Coldest night −4.1 °C at Charlotte Pass (NSW) on 2 December
Warmest night 34.6 °C at Paraburdoo (WA) on 2 January
Wettest day 402.0 mm at Napier Downs (WA) on 18 December


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 10 am on Tuesday 2 March 2010. 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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