Tuesday 1 October 2019 — Monthly Summary for Australia — Product Code IDCKGC1A00

Australia in September 2019

Temperatures Rainfall Extremes Important notes the top

In brief

• Warmer than average September for Australia
• Mean maximum temperature above average for much of Australia, and record warm for the southwest
• Mean minimum temperature below average for large areas of the north and east, warmer than average in much of Western Australia
• September rainfall below to very much below average for most of Australia; overall tenth-lowest on record nationally
• Above average rainfall for part of northwest Australia and the Alice Springs District, but totals were small as these regions are typically dry at this time of year
• It has been the second-warmest January–September on record for Australia (spanning 110 years), with rainfall also below to very much below average over most of the country, and fourth-lowest on record for Australia as a whole (spanning 120 years)

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Temperatures

September was warmer than average for Australia as a whole, with the national mean temperature 1.19 °C above average. The mean maximum temperature for the month was much warmer than average for September, coming in as the fourth-warmest September on record at +2.22 °C, while the mean minimum temperature was close to average nationally at +0.15 °C.

The national monthly diurnal temperature range (i.e. the difference between the mean maximum and mean minimum temperatures) was the second-highest on record for September at 2.07 °C (the record is +2.12 in 1980). A high diurnal temperature range is often observed in dry periods as absence of clouds is associated with lower nighttime temperatures and low humidity and soil moisture reduces latent heating (which results from vapour-liquid-solid phase changes of water).

The September mean maximum temperature was the warmest on record for Western Australia, equal-sixth-warmest for South Australia, and the seventh-warmest on record for New South Wales and South Australia. No State nor the Northern Territory placed amongst the ten warmest or coolest Septembers on record for mean minimum temperature.

The year to date has been very warm for the country as a whole; Australia observed its second-warmest mean temperature on record for January–September. The mean maximum and mean minimum temperature have also been very warm; respectively they were the highest and eighth-highest on record for Australia over the same period. Both mean temperature and mean maximum temperature for the period were warmest on record for New South Wales and for Western Australia. Many sites in Western Australia set records for warmest mean maximum temperature for September.

Maximum temperatures for September were above to very much above average for most of Western Australia except the eastern Kimberley; parts of the Northern Territory in the north, east, and south; most of Queensland except the Cape York Peninsula and a pocket of the far southwest; New South Wales; South Australia; Tasmania; and parts of northwestern and far eastern Victoria. The mean maximum temperature for the month was the highest on record over most of the southern half of Western Australia, mostly inland of the coast but extending to the coast in the Southwest and South Coastal districts.

Daily maximum temperatures were more than 10 degrees warmer than average in some areas of southeast Queensland and northeast New South Wales early in the month, including some daily records set in Queensland. This combined with very low humidity, gusty winds, and very dry fuels to lead to severe fire weather conditions. Property losses resulted in both States. Some of the most significant fires were at Sarabah, Stanthorpe/Applethorpe, and Peregian Beach in Queensland, and at Bees Nest, Shark Creek, and near Tenterfield in New South Wales. There were also numerous other fires.

Warm days elsewhere in Australia saw some daily records for high daily maximum and minimum temperatures in Western Australia in the first part of the month, for maximum and minimum temperatures in Tasmania on the 20th, and for high minimum temperatures in Victoria and New South Wales on the 21st.

The mean minimum temperature for the month was cooler than average for large parts of Australia, including eastern South Australia; much of western and northern Victoria; southern New South Wales away from the coast, and parts of the west and north; much of western Queensland, the Central Coast, Northern Tropical Coast, and Cape York Peninsula; the Top End and parts of the west and southeast of the Northern Territory; and the Kimberley in Western Australia. Some sites in the Northern Territory and Queensland observed record low September mean minimum temperature.

Warmer than average mean minimum temperatures were observed across the remainder of Western Australia, extending into parts of western South Australia; in western Tasmania; central coast New South Wales, extending into parts of the Central West Slopes and Plains; an area of the Flinders Ranges and northern Eyre Peninsula in South Australia; and a few small areas in central and southwestern Queensland.

Frost events during the first half of September led to severe frost damage to crops in southwest Western Australia, with greatest losses in the region around Esperance. Low minimum temperature records for September were set at some stations, including −5.5 °C at both Eyre and Salmon Gums Research Station. The effect of the frost was compounded by antecedent low rainfall, and high temperatures following frost early in the month, as well as crops being at a vulnerable stage of development. Early reports indicate crop damage from the frost events may be the worst for a decade or more.

Some individual cold nights during the month saw frost cause crop damage across southeastern South Australia and parts of western Victoria on the 17th and 18th, while snow fell to low levels in parts of Canberra and nearby areas of New South Wales' Southern Tablelands for several hours around midnight on the 16th/17th. Low minimum temperature records for September were set in South Australia, and Tasmania.

Some record low daily temperatures for September were also observed in the first part of the month in Queensland.

Temperature maps
	Mean	Anomaly	Deciles
Mean daily maximum temperatures
Mean daily minimum temperatures
Mean daily temperatures

Temperatures Rainfall Extremes Important notes the top

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Rainfall

Nationally, September rainfall was very much below average, ranking tenth-driest out of 120 Septembers, but nevertheless still wetter than the record dry September in 2018. Rainfall for the month was the ninth-lowest on record for September for the Murray-Darling Basin as a whole, and the fifth-lowest on record for September for Western Australia.

Rainfall was below to very much below average across most of Australia, including nearly all of New South Wales except parts of the coast; most of Queensland, except parts of the southwest, Gulf Coast, and northern Peninsula; most of Victoria, except parts of the southwest and South Gippsland; most of Tasmania, except parts of the east coast; the northern half of the Northern Territory; the southern half of Western Australia; and much of western and northern South Australia, and smaller areas of the east of that State.

Some sites in Queensland, New South Wales, and Western Australia had their lowest September total rainfall on record, or for at least 20 years.

Rainfall for September was above average for most of the Kimberley in Western Australia, extending into the northern part of the Interior District, and much of the Alice Springs District in the Northern Territory, extending east into far southwest Queensland. In all of these areas, as for most of northern Australia away from the east coast, rainfall for September is on average very low, and above average rainfall was the result of monthly totals generally on the order of 5 to 25 mm. Isolated convective showers towards the later part of September did bring totals in excess of 25 mm to some locations in the eastern Kimberley and western Alice Springs District.

A few sites in Tasmania observed a record wet day for September on the 7th, as did some sites in New South Wales on the 18th, and some sites in South Australia on the 20th.

For the year to date (January–September), rainfall has been below to very much below average over much of Australia. For Australia as a whole, it was the fourth-driest January–September on record and the driest since 1965. It was the driest January–September on record for South Australia, and amongst the ten driest on record for New South Wales, Western Australia, and the Northern Territory.

Area-average rainfall
	Rank (of 120)	Average (mm)	Departure from mean	Comment
Australia	10	6.8	−59%	10th lowest
Queensland	= 11	1.8	−86%
New South Wales	11	12.5	−64%
Victoria	24	41.6	−36%
Tasmania	27	100.1	−27%
South Australia	36	8.5	−51%
Western Australia	5	3.4	−68%	5th lowest
Northern Territory	82	4.7	−34%
Murray-Darling Basin	9	10.9	−68%	9th lowest

Rank ranges from 1 (lowest) to 120 (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
	Totals	Percentages	Deciles
Total rainfall

Temperatures Rainfall Extremes Important notes the top

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Australian weather extremes during September 2019
Hottest day	40.9 °C	at Fitzroy Crossing Aero (WA) on the 29th
Coldest day	−4.0 °C	at Mount Hotham (Vic.) on the 9th
Coldest night	−8.3 °C	at Thredbo AWS (NSW) on the 17th
Warmest night	28.0 °C	at Argyle Aerodrome (WA) on the 29th
Wettest day	158.6 mm	at Gray (Dalmayne Rd) (Tas.) on the 7th

Temperatures Rainfall Extremes Important notes the top

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