Australia in September 2021

In brief

  • Mean maximum temperatures for September were warmer than average for much of Victoria, coastal New South Wales and coastal Western Australia, southern South Australia, western and southern Queensland, and parts of northern Australia
  • Mean minimum temperatures for September were warmer than average for most of Queensland and the Northern Territory, and southern Victoria; cooler than average for parts of inland New South Wales and south-east Western Australia
  • September rainfall was below average for the southern half of Western Australia, much of South Australia, and much of the east coast, but above average for the central Northern Territory and northern Queensland, and in a band from south-west Queensland to East Gippsland in Victoria
  • For Australia as a whole, rainfall was 14% below average

Temperatures

The national mean temperature for September was 1.01 °C warmer than the 1961–1990 average for Australia as a whole. The mean maximum temperature for September was 1.31 °C warmer than average and the mean minimum temperature was 0.70 °C warmer than average.

Mean maximum temperatures for September were warmer than average for much of Australia and very much warmer than average (amongst the highest 10% of historical observations for the month) for the Top End of the Northern Territory and pockets of coastal Western Australia in the western Kimberley and Gascoyne. Large areas of inland Western Australia, Central Australia, central New South Wales, eastern Queensland, and central and southern Tasmania were close to average.

Mean minimum temperatures for September were warmer than average for most of Queensland and the Northern Territory, southern Victoria, far western South Australia, and the northern Pilbara in Western Australia. The mean minimum temperature for the month was cooler than average for parts of central to eastern New South Wales inland of the ranges, and an area of south-east Western Australia.

A high pressure system over the Tasman Sea brought generally clear skies and northerly winds over south-eastern Australia at the start of the month, with records for highest daily maximum temperature for September set at some stations in far western Victoria and south-east South on the 2nd, and record warm September daily minimum temperatures the following night at a few stations in Victoria, mostly around Melbourne.

In the Northern Territory a few stations reported their coldest September day (lowest maximum temperature) on record on the 5th.

A cold outbreak brought cool temperatures to south-east Australia around the 12th, with snow reported to relatively low levels, down to 800 m in Tasmania and 900 m in New South Wales.

Heat built over the north-west of Australia later in the month, with a low pressure centre developing on the Kimberley coast around the 20th. On the 20th and 21st some stations in the western Top End, including Darwin, and along the northern coast of Western Australia observed record high daily maximum or high daily minimum temperatures for September.

A lingering cold front on the 23rd and 24th brought cool conditions to Tasmania with snow settling to low levels overnight in parts of the west, south, and Central Plateau, including down to around 100 m elevation in the Hobart area.

Further discussion and tables of records for each state and the Northern Territory can be found in the individual regional climate summaries, which will be published on October 5th.


Areal average temperatures
Maximum Temperature Minimum Temperature Mean Temperature
Rank
(of 112)
Anomaly
(°C)
Comment Rank
(of 112)
Anomaly
(°C)
Comment Rank
(of 112)
Anomaly
(°C)
Comment
Australia 93 +1.31 = 86 +0.70 89 +1.01
Queensland 94 +1.27 99 +1.65 97 +1.46
New South Wales 86 +1.42 75 +0.45 = 81 +0.93
Victoria 87 +1.30 94 +0.60 = 94 +0.95
Tasmania 64 +0.18 69 +0.13 = 67 +0.16
South Australia 94 +1.80 = 74 +0.33 84 +1.06
Western Australia 89 +1.17 61 +0.00 79 +0.58
Northern Territory 85 +1.24 87 +1.25 88 +1.25

Rank ranges from 1 (lowest) to 112 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. 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

September rainfall was 14% below average for Australia as a whole.

Rainfall for the month was below average for the southern half of Western Australia, much of South Australia, and much of the east coast between the Central Tablelands in New South Wales and the Wide Bay and Burnett District in Queensland. For much of coastal South Australia rainfall for the month was very much below average (amongst the lowest 10% of historical observations for the month). Rainfall was above average for most of the Northern Territory south of the Top End and Gulf, northern Queensland, and in a band from south-west Queensland through western New South Wales to East Gippsland in Victoria. In Tasmania rainfall was below average for the north-east and above average for the Central Plateau to Derwent Valley.

September started with wet days in Queensland with an upper-level trough bringing showers and thunderstorms with moderate falls along the north tropical to central Queensland coast. A few stations recorded their highest September daily rainfall in the northern tropics on the 1st and moderate falls in the north-west on the 2nd.

A cold front and pre-frontal trough crossed south-east Australia early during the month, bringing widespread moderate falls to much of Victoria and New South Wales, including record high daily totals for September across much of the eastern half of Victoria on the 4th, although mostly stations with less than 30 years of record, and at a few places inland of the ranges in southern in New South Wales on the 4th or 5th.

The last days of the month also saw widespread areas of moderate to heavy rainfall across New South Wales and Victoria as a surface trough drove a band of middle to high level cloud across the eastern states and drew tropical moisture south. Low pressure centres developed on the trough as it moved eastward, and thunderstorms embedded in the cloud band saw some locally intense falls. This system brought severe thunderstorms to numerous parts of Queensland, New South Wales, Victoria and the ACT.

On the 29th severe thunderstorms brought heavy rain, hail, and flash flooding to parts of South Australia, leading to some local evacuation and disruption to road travel.

Severe thunderstorms also affected parts of New South Wales, with damaging winds, heavy rain, and hail on the 29th and 30th. Giant hail (5 to 7 cm in diameter) was reported 40 km north of Bourke, with large hail also reported at Cunnamulla and Eulo on the 29th, while on the 30th a tornado was observed at Clear Creek, near Bathurst. The tornado caused damage to houses, powerlines, and trees. Daily rainfall records for September were reported in parts of New South Wales, mostly in the northern slopes and plains, and in parts of coastal Victoria for the 24 hours to 9 am on the 30th.

Severe thunderstorms also brought giant hail to parts of southern and south-east Queensland on the 30th, with 6 centimetre hail reported on the western Darling Downs.

Further discussion and tables of records for each state and the Northern Territory can be found in the individual regional climate summaries, which will be published on October 5th.


Area-average rainfall
Rank
(of 122)
Average
(mm)
Departure
from mean
Comment
Australia 65 14.3 −14%
Queensland 80 12.1 −4%
New South Wales 91 42.4 +20%
Victoria 78 71.7 +11%
Tasmania 63 130.4 −3%
South Australia 17 6.0 −66%
Western Australia 21 5.3 −48%
Northern Territory 95 7.2 +3%
Murray-Darling Basin 93 41.6 +21%

Rank ranges from 1 (lowest) to 122 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Departure from mean is relative to the long-term (1961–1990) average.


Rainfall maps
TotalsPercentagesDeciles
Total
rainfall
Map of total rainfall Map of percentage of normal rain Map of rainfall deciles


Australian weather extremes during September 2021
Hottest day 41.5 °C Yampi Sound (Defence) (WA) on the 21st
Coldest day −2.4 °C at Mt Hotham (Vic) on the 13th
Coldest night −9.3 °C at Thredbo AWS (NSW) on the 26th
Warmest night 29.0 °C at Derby Aerodrome (WA) on the 21st
Wettest day 233.0 mm at Mt Sophia (Qld.) on the 1st


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. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the following month.

Climate Summaries are usually published on the first working day of each month.

This statement has been prepared based on information available at 1:00 pm AEST on Friday 1 October 2021. 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. Temperature area averages are derived from the ACORN-SAT version 2 dataset. Rainfall area averages, along with rainfall and temperature maps, are derived from the AWAP dataset.


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