Australia in May 2018

In brief

  • On average, days much warmer than average for Australia during May, and nights cooler than average
  • National monthly mean temperature for May somewhat above average
  • The third-driest May on record for Australia, with rainfall for the month below average across most of Australia except parts of the southeast
  • Strong cold front on the 10th brought severe winds, heavy rain, and flooding to southeast Tasmania, including Hobart

Temperatures

May was warmer than average for Australia as a whole; the national monthly mean temperature was 0.19 °C above average.

Maximum temperatures were particularly warm, with a national anomaly of +0.86 °C. Mean monthly maximum temperatures were above average for most of Australia, and in decile 10 (the warmest 10% of historical observations) for May along the west coast of Western Australia and across most of eastern New South Wales, extending into eastern Victoria and southeast Queensland, as well as for an area of the coastal Top End. Maxima were near average for South Australia, western and Gulf Country Queensland, and an area of northwestern Australia spanning the eastern Kimberley and Victoria River District in the Northern Territory.

The national mean minimum temperature was cooler than average at 0.49 °C below average for May. Minimum temperatures for the month were above average across Tasmania, southeastern South Australia, most of Victoria away from the Murray River, and across the Cape York Peninsula in Queensland. Minima were cooler than average for large areas of northern and central Western Australia and areas of that State's southern coast, for the south of the Northern Territory and the southeastern Top End, and for much of pastoral South Australia.

Abnormal warmth had dominated April, and persisted through much of May, aided by large positive surface pressure anomalies over the Great Australian Bight. With high pressure dominating the weather, it was windier than average in Tasmania and southern Victoria. The first week of the month was particularly warm, with a number of stations in Victoria, and New South Wales observing their warmest May day on record on the 3rd.

The passage of a strong cold front brought stormy weather and low temperatures to the southeast, with snow across the Alpine area and a maximum temperature of 12.8 °C on the 10th in Melbourne, which was that city's coldest day so early in the season since 1970. The cold outbreak even reached into the north of the country, with a southeast surge over the Top End dropping the minimum temperature at Darwin Airport below 20 for several days.


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 84 +0.86 43 −0.49 66 +0.19
Queensland = 76 +0.59 = 55 −0.23 69 +0.18
New South Wales 95 +1.31 56 −0.34 78 +0.48
Victoria 79 +0.61 85 +0.46 91 +0.54
Tasmania 86 +0.52 89 +0.76 95 +0.64
South Australia 58 +0.42 37 −0.57 50 −0.07
Western Australia 98 +1.40 = 39 −0.47 78 +0.46
Northern Territory 72 +0.28 26 −1.16 52 −0.43

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

May was an exceptionally dry month for Australia; nationally, May rainfall was the third-lowest on record and lowest for May since 2008 (2008 was Australia's driest May on record). Monthly total rainfall was below average for most of Australia, and in the lowest 10% of historical observations (decile 1) for May for large areas of southern Western Australia, northern and eastern New South Wales, and southern Queensland. For New South Wales as a whole May was the seventh-driest on record, while for the Northern Territory it was the ninth-driest on record.

A large number of stations in New South Wales received record low May rainfall or their lowest May rainfall for at least 20 years.

Only a few small areas received above average rainfall for the month, in southwestern and parts of southern Victoria and in parts of western, central, and southeastern Tasmania.

A large amount of this rain fell in a single event, when a complex low pressure system and strong cold front crossed Tasmania on the 10th. Record-breaking rain fell in southeastern Tasmania overnight from the 10th to 11th, particularly around Hobart, where significant flooding resulted.


Area-average rainfall
Rank
(of 119)
Average
(mm)
Departure
from mean
Comment
Australia 3 8.7 −69% 3rd lowest (record 7.8 mm in 2008)
Queensland 11 5.0 −83%
New South Wales 7 11.6 −75% 7th lowest; lowest since 2006
Victoria 61 58.2 −10%
Tasmania 77 145.5 +6%
South Australia 28 8.9 −58%
Western Australia 11 6.6 −74%
Northern Territory 9 0.4 −97% 9th lowest
Murray-Darling Basin 14 13.7 −68%

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 May 2018
Hottest day 38.3 °C    at Roebourne Aero (WA) on the 10th
Coldest day −2.6 °C    at Mount Hotham (Vic.) on the 10th
Coldest night −6.7 °C    at Perisher Valley AWS (NSW.) on the 25th and Glen Innes Airport AWS (NSW) on the 31st
Warmest night 28.5 °C    at Troughton Island (WA) on the 7th
Wettest day 236.2 mm at kunanyi (Mount Wellington Pinnacle) (Tas.) on the 11th


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 pm EST on Friday 1 June 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 May 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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