Australia in April 2018

In brief

  • Australia's second-warmest April on record, with a monthly mean temperature 2.38 °C above average (the record is +2.66 °C, set in 2005)
  • Daytime temperatures exceptionally warm across Australia, with mean maximum temperature for April amongst the five warmest on record for the Northern Territory and all States except Tasmania
  • Mean minimum temperatures also very much above average; amongst the ten warmest April mean minima for Queensland, New South Wales, South Australia, and Western Australia
  • The driest April since 1997 and the eighth-driest April on record for Australia; rainfall across southern Australia well below average
  • Exceptionally warm, dry weather associated with significant autumn fire activity, affecting South Australia and New South Wales in the first half of the month

Temperatures

April was the second-warmest on record for Australia as a whole; the national monthly mean temperature was 2.38 °C above average, just 0.28 °C behind the record set in 2005. April was warmer than average for nearly all of Australia, and particularly warm in terms of maximum temperatures. The mean monthly maximum temperature for Australia as a whole was the warmest on record at 3.17 °C. Although overnight temperatures were not as extreme, the national mean minimum temperature was still the fourth-warmest on record at 1.59 °C above average for April.

Compared to all months of the year, the national April mean temperature anomaly was the fifth-largest positive anomaly on record for any month, and the maximum temperature anomaly was the third-largest positive anomaly on record for any month.

Abnormal warmth persisted throughout all but the last week of the month. The heat, which was more characteristic of mid-summer than mid-autumn, was unprecedented in many areas in April for its intensity, its persistence or both. The spatial extent of the heat was also exceptional, with above-average maximum temperatures extending almost nationwide on each day during the first 10 days of the month. For the month as a whole records were set for record-high April mean daily maximum temperature at numerous sites in Victoria, New South Wales, South Australia, Western Australia, and the Northern Territory.

A Special Climate Statement Persistent summer-like heat sets many April records discusses the exceptional heat and records set during the first half of April; this Special Climate Statement will be updated following the end of the month to capture further records set.

Maximum temperatures were above average across nearly all of Australia, and in decile 10 (the warmest 10% of historical observations) for April across most of South Australia, northern Victoria, New South Wales away from the northeast, northwestern and inland northeastern Western Australia, and large parts of the inland west of the Northern Territory. In area-averaged terms, maxima were the highest on record for April for New South Wales and South Australia; the second-warmest for Victoria, Western Australia and the Northern Territory; and the fifth-warmest for Queensland.

Minimum temperatures for the month were also above average across most of Australia, but close to average for parts of Western Australia including the Kimberley and areas along the west coast, for the Top End of the Northern Territory, and for much of inland northern Queensland and the Cape York Peninsula. Minima were in the warmest 10% of historical observations (decile 10) for April for a large area of central South Australia. Mean monthly minima were amongst the ten warmest on record for April for New South Wales, South Australia, Queensland, and Western 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 109 +3.17 highest (was +3.10 °C in 2005) 106 +1.59 4th highest (record +2.22 °C in 2005) 108 +2.38 2nd highest (record +2.66 °C in 2005)
Queensland 105 +2.22 5th highest 103 +1.58 7th highest 106 +1.90 4th highest (record +2.69 °C in 2016)
New South Wales 109 +4.28 highest (was +4.08 °C in 2005) = 106 +2.31 equal 3rd highest (record +2.41 °C in 1990) 109 +3.30 highest (was +3.20 °C in 2005)
Victoria 108 +3.45 2nd highest (record +3.66 °C in 2005) = 95 +0.94 108 +2.20 2nd highest (record +2.45 °C in 2005)
Tasmania 84 +0.43 91 +0.60 88 +0.52
South Australia 109 +4.40 highest (was +4.33 °C in 2005) 107 +2.43 3rd highest (record +2.59 °C in 1961) 109 +3.42 highest (was +3.40 °C in 2005)
Western Australia 108 +2.99 2nd highest (record +3.06 °C in 1981) 101 +1.18 9th highest 107 +2.09 3rd highest (record +2.45 °C in 2005)
Northern Territory 108 +3.24 2nd highest (record +3.26 °C in 2005) 97 +1.44 108 +2.34 2nd highest (record +2.90 °C in 2005)

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

Australia's rainfall was very much below average for April. For the country as a whole, April was the eighth-driest on record for Australia, and the driest April since 1997. Rainfall across southern Australia was well below average, with the mainland southeast particularly dry. Rainfall for southern Australia was the third-lowest on record for April.

The month was drier than average across Victoria, New South Wales, eastern South Australia, most of Tasmania, the South West Land Division and south coast in Western Australia, large areas of southeastern, far northern, and central inland Queensland, and for numerous smaller areas scattered elsewhere. Only a very few scattered small areas, mostly about the coastline of northern Australia, received above average rainfall for the month.

Rainfall was in decile 1 (the lowest 10% of historical observations) for April for large areas, from west of Port Philip in Victoria to the far coastal southeast of New South Wales; across the Riverina in central southern New South Wales and the far west of that State; parts of the South West Land Division in Western Australia; and pockets of Queensland between the southwest and Cape York Peninsula, in eastern to central South Australia, along the east coast of Tasmania, and in the Top End. Rainfall was the lowest on record for the month at a number of stations in Victoria, and New South Wales.

The passage of a series of strong cold fronts brought a period of cold weather, damaging winds, and some moderate rainfall to southeastern Australia around mid-month, while the rest of April was mostly dry. Onshore showers brought some rainfall in central to northern Queensland throughout April, and in New South Wales during the second half of the month.

Australia's official tropical cyclone season runs from 1 November to 30 April. During the 2017–18 season, eleven tropical cyclones were recorded in the broader Australian basin (areas south of the Equator and between 90°E and 160°E, which includes Australian, Papua New Guinea and Indonesian areas of responsibility), equalling the long-term average. Five of the eleven tropical cyclones crossed the coast. Severe tropical cyclone Marcus was the strongest (category 5), having intensified over the Indian Ocean after pasing very close to Darwin at category 2 strength.


Area-average rainfall
Rank
(of 119)
Average
(mm)
Departure
from mean
Comment
Australia 8 10.2 −67% 8th lowest; lowest since 1997
Queensland 26 14.6 −65%
New South Wales 12 12.5 −73%
Victoria 11 16.1 −69%
Tasmania 33 82.3 −27%
South Australia 23 3.6 −78%
Western Australia 29 7.7 −63%
Northern Territory 34 8.3 −70%
Murray-Darling Basin 17 9.8 −74%

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 April 2018
Hottest day 43.7 °C    at Roebourne Aero (WA) on the 3rd
Coldest day 0.4 °C    at Kunanyi (Mount Wellington Pinnacle) (Tas.) on the 16th
Coldest night −5.2 °C    at Liawenee (Tas.) on the 18th
Warmest night 30.1 °C    at Thevenard Island (WA) on the 6th
Wettest day 241.0 mm at Euramo TM (Qld) on the 17th


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 Tuesday 1 May 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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