Australia in September 2013

In Brief

Last month was easily Australia's warmest September on record - averaged over Australia maximum, minimum and mean temperatures were all the warmest on record for September. The mean temperature anomaly, +2.75 °C set a record for Australia’s largest positive monthly mean temperature anomaly, for any month, displacing the previous record of +2.66 °C in April 2005. Maximum and minimum temperatures averaged over Australia were well above average, with anomalies of +3.41 °C and +2.09 °C respectively. The warm conditions were widespread across the continent, although Western Australia recorded maxima close to average in the west of that state. All states and the Northern Territory placed in the top ten records for maximum, minimum and mean, and many regions recorded their warmest month for one or more category.

September rainfall was below the long-term mean when averaged nationally (20% below the long-term average), but this disguises the contrast between the west of Australia and the remainder of the country. The majority of Western Australia recorded above-average rainfall while large areas of the remaining mainland recorded below-average monthly totals with smaller areas recording above-average rainfall, mostly across the north, New South Wales and northern Tasmania.


Temperatures

September continued the series of warmer-than-average months since mid-2012, with national area-averaged September records set for maximum temperatures (+3.41 °C), minimum temperatures (+2.09 °C) and mean temperatures (+2.75 °C). This exceptionally warm month contributed to a record-warm 12-month period (for October 2012 to September 2013), the second time the 12-month mean temperature record has been broken in as many months (see the September Climate Update for further detail).

Tasmania and Western Australia were the only states to record maxima less than two degrees above the long-term average, placing fourth- and tenth-warmest on record respectively. Anomalies for all other regions placed as either the highest or second-highest on record, ranging between +2.74 °C (Victoria) and +5.39 °C (South Australia). Maxima were near average for most of the western half of Western Australia and above average for the remainder of Australia. Maxima were highest on record for most of South Australia, the southern half of the Northern Territory and adjacent Western Australia, most of Queensland excluding the southeast and Cape York Peninsula and Carpentaria (roughly from Normanton to Torrens Creek to Townsville), New South Wales excluding the far northeast, southeast and central inland, as well as in far northwestern and coastal southwest Victoria.

Minima were highest on record for September for all states except Tasmania (third-highest on record) and Western Australia (fourth-highest on record). Minimum temperature anomalies for Tasmania and Western Australia were both less than 1.5 °C above the long-term average, with anomalies for regions other than those states ranging between +2.47 °C (Victoria) and +4.28 °C (South Australia). Minima were near average across much of the northern coast of Australia and above to very much above average across the remainder of the country. September minima were the highest on record for northwestern and southern Victoria, western New South Wales and South Australia (excluding the far northwest) and adjacent parts of the Nullarbor Plain and southeastern Northern Territory and Queensland Channel Country.

Records were also set at stations around Australia for the month as a whole, for individual daily temperature records, and for early season heat. While too numerous to list here, these records are summarised in Special Climate Statement 46 and the individual regional Climate Summaries.

Areal average temperatures
Maximum Temperature Minimum Temperature Mean Temperature
Rank* Anomaly#
(°C)
Comment Rank* Anomaly#
(°C)
Comment Rank* Anomaly#
(°C)
Comment
Australia 104 +3.41 highest 104 +2.09 highest 104 +2.75 highest
Queensland 104 +4.12 highest 99 +2.12 sixth highest 104 +3.12 highest
New South Wales 104 +4.68 highest 102 +2.17 third highest 104 +3.42 highest
Victoria 103 +2.74 second highest 104 +2.21 highest 104 +2.47 highest
Tasmania 101 +1.45 fourth highest 102 +1.54 third highest 102 +1.50 third highest
South Australia 104 +5.39 highest 104 +3.18 highest 104 +4.28 highest
Western Australia 95 +1.53 tenth highest 101 +1.21 fourth highest 101 +1.37 fourth highest
Northern Territory 104 +3.94 highest 103 +2.89 second highest 104 +3.41 highest

*A fractional rank indicates that the value is tied for that rank, ranks range from 1 (low) to 104 (high). #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
Mean
daily
temperatures
Map of mean daily temperature Map of mean daily temperature anomalies Map of mean daily temperature deciles

Rainfall

Nationally-averaged rainfall was 20% below the long-term average (area-average rainfall of 13.3 mm). Most of Western Australia received an above-average monthly total, although higher-than-average falls were patchier across the north of the state with a large area of the Interior District recording near-average falls. Western Australian rainfall was 48% above the long-term average with large areas of the greater southwest and Goldfields District recorded monthly totals in the highest 10% of records. Tasmania was the only other region to record an above average monthly total (9% above the long-term average) but the majority of the state recorded near-average monthly rainfall.

Across the remainder of Australia below-average September rainfall was recorded across most of South Australia, south of the Gulf of Carpentaria, through eastern Queensland from Townsville to the mid New South Wales coast and other scattered areas although much of the eastern states and Northern Territory recorded near-average monthly totals. Parts of the tropical north and southeastern and inland New South Wales recorded above-average monthly rainfall. The Northern Territory and Queensland both recorded around one third of their long-term average rainfall for the month, while South Australia's total was 56% below the long-term average.


Area-average rainfall
Rank
(out of 114)
Average
(mm)
Departure
from mean*
Comment
Australia 57 13.3 −20%
Queensland 23 4.1 −68%
New South Wales 45 27.6 −21%
Victoria 48 56.7 −13%
Tasmania 75 150.9 +9%
South Australia 24 7.5 −56%
Western Australia 99 15.6 +48%
Northern Territory 51 2.1 −70%
Murray–Darling Basin 47 25.1 −26%

*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 during September 2013
Hottest day    41.6 °C at Fitzroy Crossing Aero (WA) on 27 September
Coldest day    −3.1 °C at Mount Wellington (Tas.) on 11 September
Coldest night  −11.6 °C at Perisher Valley AWS (NSW) on 13 September
Warmest night    28.6 °C at Trepell Airport (Qld.) on 16 September
Wettest day  220.4 mm at Robertson (The Pie Shop) (NSW) on 17 September


Notes

The Monthly 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 EST on Tuesday 1 October 2013. 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.

The new ACORN-SAT temperature dataset has been used for calculation of State and national temperature area averages in summaries from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.


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