Australia in October 2018

In brief

  • October drier than average for southeast Australia, but welcome rain fell on the east coast
  • Rainfall somewhat below average nationally, yet third-driest for October in Tasmania
  • Australia's fourth-warmest October on record
  • Both mean maxima and mean minima warmer than average for October across most of Australia
  • Mean minima in the top ten for October for the Northern Territory and all States except Victoria
  • Mean maxima in the top ten for Queensland, Victoria, Tasmania, and the Northern Territory

Temperatures

October was an exceptionally warm month for Australia. The national monthly mean temperature was the fourth-highest on record for October at 1.83 °C above average. For Australia as a whole, mean minima were the second-highest on record for October, some 1.81 °C warmer than average for the month. Mean maxima were the ninth-highest on record, with days 1.84 °C warmer than the long-term mean.

The year to date has also been very warm for most of Australia, with mean temperatures in decile 10 for the ten months to October across a great deal of Australia. Compared to other January to October periods, the area-averaged mean temperature for Australia was the fifth-warmest on record. It has been an especially warm year so far for New South Wales—the warmest on record compared to other January to October periods.

Both minimum and maximum temperatures were above average for most of Australia. Monthly mean minimum temperatures were in the warmest 10% of historical observations (decile 10) for the south of Western Australia, most of South Australia and New South Wales, Queensland south of Carpentaria and most of the Northern Territory away from the Top End and northeast, and for nearly all of Tasmania. Victoria was the only State to place outside of the warmest ten Octobers on record for mean minimum temperature. Maxima were in decile 10 for most of Tasmania and Victoria, the Riverina in New South Wales, most of the Kimberley in Western Australia, the Top End and east of the Northern Territory, northeastern South Australia, the extreme northwest of New South Wales, and most of Queensland away from the southeastern quarter and lower Cape York Peninsula. For Queensland, the Northern Territory, Victoria, and Tasmania, area-averaged mean maxima were amongst the ten warmest on record for October.

The period around the middle of the month was particularly warm for the southeast, owing to north- to northeasterly winds associated with a high pressure system over the southern Tasman Sea. A few sites in Tasmania and Victoria had their warmest October night on record on the 16th or 17th. For the month as a whole, monthly mean minima were the warmest on record for October at some sites in Tasmania and New South Wales.

Maxima were close to average for much of the western half of Western Australia and in coastal New South Wales and southeast Queensland, associated with cloudy conditions and above average rainfall along the east coast. Only a narrow coastal margin of New South Wales observed cooler than average days. Mean minima were close to average or cooler than average in some isolated pockets scattered across northern Australia.


Areal average temperatures
Maximum Temperature Minimum Temperature Mean Temperature
Rank
(of 109)
Anomaly
(°C)
Comment Rank
(of 109)
Anomaly
(°C)
Comment Rank
(of 109)
Anomaly
(°C)
Comment
Australia 101 +1.84 9th highest 108 +1.81 2nd highest (record +2.34 °C in 2015) 106 +1.83 4th highest (record +2.89 °C in 2015)
Queensland 106 +2.06 4th highest (record +3.10 °C in 1988) 106 +1.93 4th highest (record +2.41 °C in 2005) 107 +1.99 3rd highest (record +2.68 °C in 1988)
New South Wales 97 +2.42 108 +2.45 2nd highest (record +3.54 °C in 2015) 107 +2.44 3rd highest (record +4.52 °C in 2015)
Victoria 104 +2.56 6th highest = 97 +0.98 105 +1.77 5th highest
Tasmania 105 +1.56 5th highest 100 +0.67 10th highest 103 +1.12 7th highest
South Australia 97 +2.11 107 +1.91 3rd highest (record +3.65 °C in 2015) 104 +2.01 6th highest
Western Australia =88 +1.22 101 +1.47 9th highest 98 +1.35
Northern Territory 107 +2.03 3rd highest (record +2.58 °C in 1988) 104 +2.04 6th highest; highest since 2005 108 +2.03 2nd highest (record +2.41 °C in 1988)

Rank ranges from 1 (lowest) to 109 (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

The first nine months of 2018 were exceptionally dry over the southeastern quarter of the mainland, resulting in significant rainfall deficiencies. October brought some welcome rainfall across the east coast, and in much of inland and southeast Western Australia, but above average rainfall missed many on the areas experiencing serious or severe rainfall deficiencies, and was below to very much below average for much of southeastern Australia. The Drought Statement, to be released shortly, will discuss changes to rainfall deficiencies in greater detail.

Overall, October was somewhat wetter than average for Australia. Rainfall for the month was above average along the east coast of Australia from the Illawarra in New South Wales, through eastern Queensland, and across large parts of Cape York Peninsula and the Gulf Country. For much of coastal southeast Queensland, and the Northern Rivers and Mid North Coast districts of New South Wales, rainfall was in the highest 10% of historical rainfall totals (decile 10) for the month. Some sites in both New South Wales and Queensland had their wettest October day on record, or their highest October total rainfall on record. Thunderstorms produced much of this rainfall, with a number of severe storms occurring during the month, several of which resulted in significant damage in parts of southeast Queensland.

Rainfall was also above average for much of Western Australia and in decile 10 for a large area focused on the Goldfields District. Above average rainfall extended into the southwest of the Northern Territory and the west of South Australia. Rainfall was mostly close to average across the southwest of Western Australia, and average to below average around the northern Gascoyne, Pilbara, and Kimberley.

In southeastern Australia rainfall was below to very much below average for southeast South Australia, most of Victoria away from the northwest, and all of Tasmania. Rainfall was in the lowest 10% of historical rainfall totals (decile 1) for the month in western to central Tasmania, South and West Gippsland, and other isolated pockets in northern and eastern Australia, including areas scattered along the Victorian coastline. For Tasmania as a whole it was that State's third-driest October on record, with fewer cold fronts and westerly winds than is typical for the time of year. Tasmania's area-averaged rainfall was 60% below the long-term mean.


Area-average rainfall
Rank
(of 119)
Average
(mm)
Departure
from mean
Comment
Australia 83 25.9 +11%
Queensland 88 34.3 +34%
New South Wales 84 48.7 +10%
Victoria 18 30.1 −53%
Tasmania 3 49.6 −60% 3rd lowest (record 20.7 mm in 2015)
South Australia 68 15.2 −17%
Western Australia 105 19.0 +49%
Northern Territory 82 20.0 +6%
Murray-Darling Basin 62 36.6 −9%

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


Australian weather extremes during October 2018
Hottest day 44.4 °C    at Birdsville Airport (Qld.) on the 26th
Coldest day −0.2 °C    at Mount Baw Baw (Vic.) on the 10th
Coldest night −6.7 °C    at Perisher Valley AWS (NSW) on the 28th
Warmest night 30.1 °C    at Birdsville Airport (Qld.) on the 27th
Wettest day 173.4 mm at Lower Springbrook Alert (Qld.) on the 16th


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 month.

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

This statement has been prepared based on information available at 1:30 pm EST on Thursday 1 November 2018. 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.

The system used for calculating areal averages of rainfall was changed in May 2009; the main effect was that current and historical values for Tasmania were increased. Since December 2012, ACORN-SAT has been used for calculating areal averages of temperature; the major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, and hence rankings are calculated using a larger set of years.


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