Thursday 1 March 2018 — Seasonal Climate Summary for Australia — Product Code IDCKGC1A00

Australia in summer 2017–18

Temperatures Rainfall Extremes Important notes the top

In Brief

• An exceptionally warm summer for Australia; nationally the second-warmest summer on record
• Maxima and minima both exceptionally warm for Australia as a whole, though daytime temperatures cooler than average for Western Australia's northwest and interior
• Western Australia the only region to rank outside the top ten for summer mean temperature, associated with very much above average rainfall, particularly during January
• Consistently warm across eastern Australia in all three months
• Rainfall above average in Western Australia and the Top End of the Northern Territory, below average for most of eastern Australia; near average nationally
• Generally wetter than average for the west; drier than average for the east in each month, but December rainfall very much above average for parts of the southeastern mainland

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Temperatures

Summer 2017–18 was exceptionally warm for Australia. All regions except Western Australia observed mean temperatures for the season amongst the ten warmest on record, and for Australia as a whole it was the second-warmest summer on record (1.00 °C above the long-term average). Both maximum and minimum temperatures were also very much above average for Australia, with minima the warmest on record for summer (0.96 °C) and maxima the fourth-warmest on record for summer (1.04 °C).

Daytime temperatures for summer were above average for the eastern States (Queensland, New South Wales, Victoria and Tasmania), South Australia, and most of the Northern Territory away from the Victoria River District. Maxima were in the highest 10% of historical observations (decile 10) for most of the eastern States, the southern half of the Northern Territory, and the eastern half and southwest of South Australia. Cooler than average summer mean maxima were observed over the northwest and interior of Western Australia, associated with very much above average rainfall in this region.

Mean minimum temperatures were above to very much above average for the majority of Australia. Minima were in the highest 10% of historical observations (decile 10) for much of the eastern States, the eastern half of South Australia, southwest of the Northern Territory, and areas of Western Australia between the south coast and Northwest Cape. Minima were, however, near average along the east coast of Queensland from the Central Coast District to the northern Cape York Peninsula, across most of the north and west of the Northern Territory, and in Western Australia's Kimberley, Interior and South West.

Each of the individual months of summer was warmer than average nationally. Both maxima and minima were warmer than average across the majority of eastern Australia for each month. Night-time temperatures during December were particularly warm for the southeast, with monthly mean minima were the warmest on record for Tasmania and along the coast of the southeastern mainland between Western Port, east of Melbourne, the central coast of New South Wales. Maxima were cooler than average for much of Western Australia for January and February, largely associated with the passage of tropical lows and cyclones, while monthly mean minima were cooler than average for both months in a smaller area of Western Australia.

Summer's exceptional warmth was more the result of prolonged, widespread, low-intensity warm weather rather than individual heatwaves. However, a number of places did set records for warmth across the season. There were a few records in western Queensland for warmest summer mean maxima, though mostly for stations with less than 20 years of observations. Some stations in New South Wales, mostly around Sydney, observed their warmest summer mean maxima or mean minima. Some, mostly coastal stations, observed their warmest summer mean minima in Victoria and Tasmania, and some stations in eastern Tasmania also set records for warmest summer mean maxima.

Nevertheless, a number of periods of very warm weather did occur during the season. December records were set at multiple stations in New South Wales and South Australia. In early January very hot days were observed around the Sydney region, including 47.3 °C at Penrith Lakes AWS on the 7th, which is Greater Sydney's second-warmest day on record for any time of year. At the end of January some very warm mornings saw multiple stations in northern Tasmania set summer records for highest daily minimum temperature, with a few stations also setting records in Victoria. A prolonged warm spell during February saw a number of stations in Queensland set February records and Queensland observed its warmest February day—in area-averaged terms—with a statewide mean maximum temperature of 40.46 °C on the 12th.

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

Summer rainfall was near average overall. Rainfall for the season was above average for most of Western Australia, the western half of South Australia, most of the Top End of the Northern Territory, most of southern New South Wales, and most of the eastern half of Victoria. The season was drier than average for most of Queensland, the east of the Northern Territory south of the Gulf of Carpentaria, much of northern and eastern New South Wales, the western half of Victoria, and far southeastern South Australia.

Summer was the tenth-wettest on record for Western Australia, and a number of stations in the north and southwest of Western Australia observed their highest total summer rainfall on record.

Western Australia received above average rainfall during each month of summer, with particularly heavy rainfall during January and February accompanying several tropical lows and cyclones contributing to monthly rainfall records at a number of stations in Western Australia and the Northern Territory. Daily rainfall records were also broken for December by tropical cyclone Hilda at a number of stations in the western Kimberley. In mid-January the remnant low associated with tropical cyclone Joyce produced daily rainfall records for the month or season along parts of the west coast of Australia during mid-January, including in the Perth region. During mid-February tropical cyclone Kelvin broke daily rainfall records for February at some stations in the Kimberley. Broome Airport, with a January–February total of more than 1550 mm, has already exceeded the previous annual rainfall record set at a nearby, but now closed, station (1496.6 mm in 2000).

Record-breaking rain also visited southeastern Australia during the season. In the first days of December a blocking high over the Tasman Sea drew moist tropical air into the southeast, with very heavy rain leading to flash flooding and daily rainfall records for December in Victoria, southern New South Wales, and northern Tasmania. Some stations in northern Victoria had their wettest day on record for any month of the year.

Summer rainfall was in the lowest 10% of historical observations (decile 1) for much of central inland and western Queensland, with below average rainfall over most of the region during each month. Summer was the driest on record for some stations in western Queensland, with a number of other stations having their lowest summer rainfall for several decades. In general, after a very wet start to the northern wet season in October and above average February rainfall in the greater southeast, November to February have seen below average rainfall across large parts of Queensland for the wet season to date, and rainfall deficiencies are in place for parts of the State.

Area-average rainfall
	Rank (of 118)	Average (mm)	Departure from mean	Comment
Australia	77	221.0	+6%
Queensland	15	222.9	−31%
New South Wales	43	130.7	−23%
Victoria	71	127.1	+6%
Tasmania	47	233.8	−4%
South Australia	79	65.5	+6%
Western Australia	109	261.2	+75%	10th highest
Northern Territory	67	331.0	+5%
Murray-Darling Basin	42	112.8	−22%

Rank ranges from 1 (lowest) to 118 (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 in summer 2017–18
Hottest day	47.4 °C	at Marree Aero (SA) on 22 January, Wudinna Aero (SA) on 19 January, and Birdsville Airport (Qld) on 29 December
Coldest day	2.3 °C	at kunanyi (Mount Wellington Pinnacle) (Tas.) on 3 December
Coldest night	−3.2 °C	at Perisher Valley AWS (NSW) on 1 February
Warmest night	34.4 °C	at Birdsville Airport (Qld) on 12 January
Wettest day	448.8 mm	at West Roebuck (WA) on 30 January

Temperatures Rainfall Extremes Important notes the top

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