Australia in October 2015

In brief

October rainfall was below average for most of Australia, although above average for most of the northern half of Western Australia. Monthly rainfall was the lowest on record for most of Tasmania and an area spanning the southwest of Victoria and southeastern South Australia. For Tasmania as a whole, it was the driest October on record, while for Victoria it was the seventh-driest October and for South Australia the equal-seventh driest. Nationally, rainfall was 53% below average.

Both maximum and minimum temperatures were very much above average to warmest on record for the southern half of Australia for October, and the highest on record for the nation as a whole (national maximum temperature anomaly +3.44 °C, minimum temperature anomaly +2.34 °C). The national mean temperature anomaly of +2.89 °C was the warmest monthly anomaly on record for any month, surpassing the previous record of +2.75 °C set in September 2013. The extreme monthly anomalies were a result of exceptional early-season warmth at the start of the month and persistence of above-average temperatures throughout the month as a whole. Records associated with the early-season heat were summarised in a Special Climate Statement—this statement will shortly be updated to include discussion of the records broken for the month as a whole (the updated statement will be available from the Special Climate Statement page).

Bucking the trend, the east of the Cape York Peninsula in Queensland observed cooler-than-average days for October, while nights were cooler than average for the Top End of the Northern Territory and other isolated pockets of northern Australia.


Temperatures

The national October mean temperature was 2.89 °C above the long-term mean and the highest on record for any month of the year (surpassing the record of +2.75 °C set in September 2013). Maximum and minimum temperatures were also the warmest on record nationally for October, with respective anomalies of +3.44 °C for maxima (also warmest on record for any month, surpassing the record of +3.41 °C set in September 2013) and +2.34 °C (placing fourth-warmest on record for any month).

All States and the Northern Territory placed in the top ten maximum temperature records for October; New South Wales, Victoria, South Australia, and Western Australia observed their warmest October on record. All regions except Tasmania and the Northern Territory placed in the top ten minimum temperature records for October.

Spatially, maximum temperatures were warmest on record across nearly all of Australia south of a line running from the northern boundary of the Gascoyne in Western Australia, through Alice Springs in the south of the Northern Territory, then through southwestern Queensland to northeastern New South Wales. Days were warmer than average for the Kimberley in Western Australia, most of the remainder of the Northern Territory, western and southern Queensland and northeastern New South Wales. Days were cooler than average for the east of the Cape York Peninsula in Queensland. The area of Australia observing highest-on-record maximum temperatures was the largest for any October (highest-on-record maximum temperatures covered 54.7% of the country; the previous record area was 22.3% in 1988, and no other October has seen more than 10% of the country record warm).

Minimum temperatures were warmest on record for most of Australia south of a line parallel with the border between the Northern Territory and South Australia, although warmer than average to much warmer than average for the north of the South West Land Division in Western Australia, parts of the southeast, and all of Tasmania. Night-time temperatures were near average for the eastern Kimberley, the north and west of the Northern Territory, and along the east coast of Queensland, with areas of cooler-than-average nights observed in most of the Top End and isolated pockets of northern Australia.

A significant and prolonged heatwave near the start of October saw early-season temperature records set across much of southern Australia, some stations observing their warmest October day on record (including 13 in Victoria setting records on the 5th or 6th), and others setting records for the length of runs of consecutive warm days. The hot spell was a result of a ridge of high pressure which tracked across southern parts of the continent, followed by a pre-frontal trough, which together directed very warm air from the north of Australia into southern regions, with abnormal heat spreading from the west of Australia at the start of the month through the southeast by the latter part of the first week of October (see Special Climate Statement 52 for more details).

Above-average temperatures continued throughout the month, with a second pulse of warm temperatures passing across the south just prior to mid-month, and again between the 21st and 25th. A large number of stations in the southern half of the country observed monthly records for mean, maximum, or minimum temperatures—see individual regional summaries for details. The Special Climate Statement issued early in October will be updated shortly to include discussion of October as a whole and the further records set.


Areal average temperatures
Maximum Temperature Minimum Temperature Mean Temperature
Rank
(of 106)
Anomaly
(°C)
Comment Rank
(of 106)
Anomaly
(°C)
Comment Rank
(of 106)
Anomaly
(°C)
Comment
Australia 106 +3.44 highest (was +2.76 °C in 2014) 106 +2.34 highest (was +1.64 °C in 1988) 106 +2.89 highest (was +2.14 °C in 1988)
Queensland = 97 +1.60 equal 9th highest 101 +1.42 6th highest 101 +1.51 6th highest
New South Wales 106 +5.50 highest (was +4.06 °C in 2014) 106 +3.54 highest (was +1.86 °C in 1965) 106 +4.52 highest (was +2.58 °C in 2014)
Victoria 106 +5.93 highest (was +4.98 °C in 1914) 106 +2.33 highest (was +1.66 °C in 1963) 106 +4.13 highest (was +2.99 °C in 1914)
Tasmania 104 +2.16 3rd highest (record +3.20 °C in 1914) 91 +0.48 103 +1.32 4th highest (record +1.91 °C in 1963)
South Australia 106 +5.60 highest (was +4.14 °C in 2014) 106 +3.62 highest (was +1.92 °C in 1940) 106 +4.61 highest (was +2.80 °C in 2014)
Western Australia 106 +3.73 highest (was +2.86 °C in 2014) 106 +2.81 highest (was +2.05 °C in 2014) 106 +3.27 highest (was +2.46 °C in 2014)
Northern Territory 105 +2.05 2nd highest (record +2.58 °C in 1988) = 91 +1.00 98 +1.53 9th highest

Rank ranges from 1 (lowest) to 106 (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

Nationally-averaged rainfall during October was 53% below the long-term mean. Rainfall was below to very much below average over most of Australia, and in the lowest 10% of historical observations (decile 1) for much of the South West Land Division in Western Australia, a stretch along the southern coast from around Ceduna in South Australia through to South Gippsland in Victoria, all of Tasmania, large areas in central Australia and western Queensland, and smaller parts of southern New South Wales, eastern South Australia, and the Top End.

Rainfall was the lowest on record for October for most of Tasmania and an area spanning the southwest of Victoria and southeastern South Australia. A very large number of stations observed their driest October on record in Tasmania (including 36 stations with at least 50 years of records), as did a smaller number of stations in Victoria and a few in South Australia. For Tasmania as a whole, it was the driest October on record, while for Victoria it was the seventh-driest October and for South Australia the equal-seventh driest.

The northern half of Western Australia recorded above-average rainfall for the month. October is typically a dry month for this part of the country and monthly rainfall totals were generally in the range of 10 to 25 mm; falling as isolated showers throughout the month and more widespread areas of generally light falls surrounding pockets of moderate totals towards the end of the month.

In the east of Australia, a large portion of the rain that did fall was associated with storms and showers—some severe. Intense thunderstorms associated with a surface trough extending from central Australia into the southeast produced heavy, but scattered, rainfall totals over parts of Melbourne and eastern Victoria between the 10th and 12th. As the trough tracked eastward showers and storms occurred over northeastern New South Wales and southeastern Queensland in the 48 hours to 9 am on the 15th.

Showers and storms again brought rainfall to Tasmania, the eastern half of Victoria, and central to eastern New South Wales between the 20th and 21st, with widespread falls along the east coast on the following day. Rainfall was more widespread in New South Wales and southeastern Queensland between 24th and the end of the month, including some severe thunderstorms which caused widespread damage in Fernvale on the 27th and in Chinchilla on the 28th. The 24 hours to 9 am on the 31st also saw showers and thunderstorms over parts of the southeast, southwest, and northwest of Australia.


Area-average rainfall
Rank
(of 116)
Average
(mm)
Departure
from mean
Comment
Australia 11 10.8 −53%
Queensland 32 13.4 −48%
New South Wales 25 21.7 −51%
Victoria 7 17.7 −72% 7th lowest
Tasmania 1 20.6 −83% lowest
South Australia = 7 3.5 −81% equal 7th lowest
Western Australia 65 11.0 −14%
Northern Territory 20 4.3 −77%
Murray-Darling Basin 16 17.7 −56%

Rank ranges from 1 (lowest) to 116 (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 2015
Hottest day 44.6 °C at Port Hedland Airport (WA) on 25 October
Coldest day   3.0 °C at Kunanyi (Mount Wellington Pinnacle) (Tas.) on 22 October
Coldest night −6.4 °C at Liawenee (Tas.) on 17 October
Warmest night 29.3 °C at Halls Creek Comparison (WA) on 27 October
Wettest day 95.4 mm at Nitmiluk Rangers (NT) on 31 October


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 10 am EST on Monday 2 November 2015. 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 August 2009; the main effect was that current and historical values for Tasmania were increased. Since August 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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