Friday 1 March 2019 — Seasonal Climate Summary for Australia — Product Code IDCKGC1A00

Australia in summer 2018–19

Temperatures Rainfall Extremes Important notes the top

In Brief

• Australia's warmest summer on record, marked by persistent widespread heat
• Mean and maximum temperature for the season broke previous records by large margins; both almost one degree above the record set in 2012–13
• Warmest on record for New South Wales, Victoria, Western Australia, and the Northern Territory
• Summer second-warmest on record for Tasmania and South Australia, fourth-warmest for Queensland
• Exceptional heatwaves during early December on the tropical Queensland coast and across much of Australia during December and January
• Significant fires affecting eastern Queensland, large parts of Tasmania, eastern Victoria, northeastern New South Wales, and South West Western Australia
• Rainfall below to very much below average across most of Australia, but above average for large parts of northern Queensland
• Severe tropical cyclone Owen caused flooding in the Queensland's eastern Cape York Peninsula in mid-December, and contributed to thunderstorms over southeast Australia, with flooding in western and northern Victoria
• Active monsoon trough and slow-moving low from late January to early February produced extremely heavy rainfall , with very large areas of flooding in northern Queensland
• Delayed and generally weak monsoon; onset at Darwin 23 January, 2 days short of latest on record
• Severe thunderstorms with giant hail over eastern New South Wales on 20 December caused extensive property damage, including in Sydney and the Blue Mountains
• Dust storms originating from Central Australia affected the east on several occasions; one storm in mid-February stretched over 1500 km

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Temperatures

Summer 2018–19 was Australia's warmest summer on record.

The national mean temperature for summer was 2.14 °C warmer than the 1961–90 average, breaking the previous record (+1.28 °C in 2012–13) by a large margin. The mean maximum temperature for summer also broke the national record (was +1.64 °C in 2012–13) by a similar margin, with the 2018–19 summer mean maximum temperature 2.61 °C warmer than average, while the mean minimum temperature broke the record by a smaller, but still substantial, margin at 1.67 °C warmer than average (record was +1.09 °C in 2017–18).

It was exceptionally warm across most of the country, with summer the warmest on record for New South Wales, Victoria, Western Australia, and the Northern Territory, second-warmest for Tasmania and South Australia, and fourth-warmest for Queensland. Both maximum and minimum temperatures for the season were exceptionally warm, with only the mean maximum temperature for Queensland (ranked equal-seventh) placing outside the top three warmest on record. Some of the regions broke their existing records by very large margins, e.g. mean maximum temperature for the Northern Territory (new record +3.25 °C, old record +1.76 °C) and mean minimum temperature for New South Wales (new record +3.21 °C, old record +2.33 °C).

Mean maximum temperature was very much above average across most of Australia, except across Queensland's Cape York Peninsula and the northeast of the State, and along the coastal fringe in Western Australia's Pilbara, west coast, and parts of the south coast. The mean summer maximum temperature was highest on record for large areas of northern Australia outside of Queensland; northern South Australia and an area of the Nullarbor; western and northeastern New South Wales; much of Victoria away from the extreme west and southwest; and eastern Tasmania.

Minimum temperature was also very much warmer than average in most areas. Summer mean minimum temperature was highest on record for summer for most of New South Wales away from the northeast and far west, adjacent parts of southern inland Queensland and central northern and eastern Victoria; pockets of Queensland's Gulf Country and northeast Peninsula; and a large area spanning the central Northern Territory and northern Interior and eastern Pilbara in Western Australia. The mean minimum temperature for the season was near-average along the west and south coast of Western Australia, and cooler than average in a few isolated pockets.

Summer 2018–19 comes on the back of a string of warm months and warm seasons for Australia. This pattern is consistent with observed climate change. As the State of the Climate 2018 report outlines, Australia has warmed by over one degree since 1910, with most warming occurring since 1950. This means that natural climate variability sits on top of this background warming, and temperature records are likely to continue to be broken in the coming years.

The delayed onset on the monsoon, and generally weak monsoonal activity across northern Australia outside of northern Queensland, facilitated the build-up of heat over the continent during early summer, while persistent slow-moving blocking high pressure systems over the Tasman Sea and a notable absence of strong cold fronts in the south maintained the persistent heat.

Exceptional heatwaves affected large areas of Australia, in early December on the tropical Queensland coast and across much of Australia during December and January. The latter heatwave was unprecedented in scale and duration. Many records were set across summer for individual daily extremes, warm monthly average temperatures at individual locations, and for long runs of consecutive warm days. Further details can be found the in the Special Climate Statements for the early December and December–January events, and in the individual summer summaries for the States and Northern Territory.

A number of significant fires also occurred during the season.

• In Queensland fires associated with the extreme heatwave had been active across the east of the state from late November, and continued into December, burning 1 011 702 ha by 6 December.
• Lightning strikes in late December and mid-January igniting numerous fires across Tasmania, several of which still burned at the end of summer. In total about 200 000 ha burnt, including over 88 000 ha in the Tasmanian Wilderness World Heritage Area.
• Fires burned from early and mid-January in Gippsland in Victoria, reaching 12 418 ha at Rosedale near Traralgon and 22 695 ha at Timbarra in the east by the end of summer, while fires started on the east side of Melbourne's largest water storage, Thomson Dam, in late January and at Walhalla south of the Dam in late February, reaching 6300 ha and 8775 ha respectively by the end of the month.
• Two significant fires affected northeast New South Wales during February; at Tingha, burning more than 23 000 ha and 13 homes, and at Tabulam west of Casino, burning 7000 ha.
• A fire during the second half of February in the shires of Donnybrook-Balingup and Nannup in South West Western Australia burnt more than 4000 ha.

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

Rainfall for summer was below to very much below average for most of Australia. For the nation as a whole, it was the seventh-driest summer on record, despite very heavy rain in parts of northern Queensland.

Rainfall was very much below average, in the lowest 10% of historical observations, across much of the Northern Territory; northeastern and central southern South Australia; across the southeastern quarter of Queensland, extending into northern New South Wales, and along the western end of the border between the two States; in large areas around the north, west, and south coast of Western Australia; and in small pockets of West and South Gippsland in Victoria, focused about the southern ranges, and in southern Tasmania.

Many sites in southern Queensland, Western Australia, and New South Wales observed their driest summer on record, as did some sites in South Australia.

A delayed and generally weak monsoon contributed to the fourth-lowest total summer rainfall on record for the Northern Territory, and fifth-lowest on record for Western Australia. In Darwin, monsoon onset did not occur until 23 January (the second-latest on record, behind 1972–73), which is nearly a month later than usual. In the south of the country, long-lived blocking high pressure systems over the Tasman Sea and a lack of strong cold fronts contributed to below average rainfall.

In stark contrast to most of the rest of Australia, several intense rainfall events contributed to above or very much above average rainfall along the northeast coast, northern interior and northwest of Queensland, resulting in record high summer rainfall totals at a large number of sites in northern Queensland. Rainfall was also above average for a pocket of northwest Victoria, following storms and flash flooding in mid-December associated with tropical cyclone Owen.

Severe tropical cyclone Owen caused flooding on the east of Queensland's Cape York Peninsula in mid-December, and contributed to thunderstorms over southeastern Australia, producing heavy rain and flooding in western and northern Victoria. Torrential rainfall affected the east coast as Owen decayed, passing from land into the Coral Sea, including a new Australian daily rainfall for December of 678 mm in the 24 hours to 9 am AEST on the 16th at Halifax Macrossan Street, east of Ingham.

From 24 January to early February, an active monsoon trough and a slow-moving monsoonal low produced extremely heavy rainfall over tropical Queensland. The system produced 11 consecutive days of heavy rain in some areas, with daily rainfall records at some sites, as well as multi-day total records as some locations received a year's worth of rain in a two-week period. For example, Townsville Aero received 1339.8 mm in the 11 days to 9 am on 8 February (a new record). The average rainfall at Townsville Aero (based on all years since 1940) is 701.4 mm for summer, and 1127.9 mm for the year as a whole.

Flooding resulted in northern Queensland on the coast between Daintree and Mackay, parts of the western Peninsula, and across the Gulf coast. The flooding in the Gulf catchments was extensive, and continued well into February, including in some rivers which drain inland. At the end of the February floodwater had reached Goyder Lagoon, in far northeastern South Australia, and some of this water will make its way to Lake Eyre / Kati Thanda over the coming weeks.

Area-average rainfall
	Rank (of 119)	Average (mm)	Departure from mean	Comment
Australia	7	142.7	−32%	7th lowest; lowest since 1982–83
Queensland	61	322.8	−1%
New South Wales	10	88.3	−48%	10th lowest; lowest since 1984–85
Victoria	44	104.8	−12%
Tasmania	21	189.4	−22%
South Australia	13	22.1	−64%
Western Australia	5	76.8	−49%	5th lowest; lowest since 2004–05
Northern Territory	4	159.9	−49%	4th lowest (record 141.6 mm in 1951–52)
Murray-Darling Basin	6	66.8	−54%	6th lowest; lowest since 1984–85

Rank ranges from 1 (lowest) to 119 (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 2018–19
Hottest day	49.5 °C	at Port Augusta Aero (SA) on 24 January
Coldest day	3.5 °C	at Mount Baw Baw (Vic.) on 13 February and Mount Read (Tas.) on 12 February
Coldest night	−3.0 °C	at Mount Hotham (Vic.) on 13 February
Warmest night	36.6 °C	at Wanaaring (Borrona Downs AWS) (NSW) on 26 January
Wettest day	678.0 mm	at Halifax Macrossan St (Qld) on 16 December

Temperatures Rainfall Extremes Important notes the top

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