Australia in April 2015

In brief

April rainfall was higher than average for much of the mainland southeastern States, notably along the coast of New South Wales where an East Coast Low brought exceedingly heavy rainfall during the latter part of the month. Rainfall was also above average across eastern parts of South Australia and for much of western to central Western Australia. Rainfall was below average in parts of the north, and very much below average in Tasmania, which had its fifth-driest April on record. Nationally, rainfall was 12% below average.

Maximum temperatures for April were cooler than average across the southern half of the mainland, particularly through interior parts of Western Australia and southern parts of South Australia, with warmer-than-average days only recorded in the coastal north and adjacent hinterlands. Nationally, maximum temperatures were 1.02 °C cooler than average, making it Australia's 18th-coolest April in 106 years of records. Minimum temperatures were generally closer to average, with the national average coming in at 0.36 °C below average. Parts of New South Wales and the coastal west and far northern Queensland observed warmer-than-average nights, while nights were cooler than average in eastern Queensland, central Australia and small areas along the mainland south coast.


Temperatures

The national April mean temperature was 0.68 °C below average. Both maximum and minimum temperatures contributed to this anomaly, at 1.02 °C and 0.36 °C cooler than average respectively. Generally, maximum temperatures showed stronger deviation from mean than minima. Maximum temperatures were warmer than average or very much warmer than average across the eastern Kimberley, the Top End, around the Gulf of Carpentaria, and across the Cape York Peninsula and adjacent regions of northern Queensland. Warmth in this region followed a record warm spell in March, and indeed saw further monthly records set in some parts of the north.

However, over most of the remainder of the mainland maximum temperatures were below to very much below average. Daytime temperatures were more than two degrees cooler than average through the Pilbara, Gascoyne, Interior and southern districts of Western Australia, as well as southern parts of South Australia. Just over 60% of Western Australia recorded maximum temperatures in the lowest 10% of records (decile 1) for the month, leading to that State's sixth-coolest April on record for maximum temperatures with a number of daily and monthly records set (see the Western Australian monthly summary for details). South Australia recorded its 11th-coolest April and coolest April in 32 years, and nationally it was the 18th-coolest April on record. Below-average maxima were recorded across all of Western Australia except the Kimberley and a very narrow coastal fringe in the west, across central Australia and nearly all of South Australia, most of New South Wales, southeast Queensland away from the coast, and both western and eastern Victoria.

Minimum temperatures were warmer than average in eastern New South Wales and the coastal west of Western Australia where cloud cover associated with above-average rainfall kept nights warmer. Minima were also above average in a small area of southeast Western Australia, and areas around the coast of the Cape York Peninsula. Minima were below average through central Australia, an area of eastern Queensland extending into the Central Highlands District, and smaller areas of western Victoria, southeastern and southern agricultural South Australia, western Tasmania and between the central south coast and inland Pilbara in Western Australia.


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 18 −1.02 47 −0.36 29 −0.68
Queensland = 60 +0.24 54 −0.17 = 57 +0.03
New South Wales 22 −1.04 76 +0.40 47 −0.31
Victoria 33 −1.06 = 60 −0.35 41 −0.70
Tasmania 47 −0.54 = 40 −0.68 46 −0.60
South Australia 11 −2.11 = 31 −0.78 18 −1.44
Western Australia 6 −1.78 6th lowest = 44 −0.32 11 −1.04
Northern Territory 45 −0.44 36 −0.85 39 −0.64

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 April was 12% below the long-term mean. The mainland southeastern States and Western Australia recorded area-averaged totals above the long-term mean, while Tasmania had its fifth-driest April on record. All but the eastern third of Tasmania received April rainfall in the lowest 10% of records (decile 1).

Tasmania was the most anomalously dry region during April, but large areas of the north of both the Northern Territory and of Queensland also observed below-average rainfall for the month, as did a region of the central Gascoyne in Western Australia.

Rainfall was above to very much above average for most of New South Wales, extending into East Gippsland in Victoria, parts of southern Queensland, and covering most of eastern South Australia and the West Coast District of South Australia. Areas of southeastern South Australia and western Victoria already experiencing rainfall deficits received only average to below-average rainfall for the month. Large areas of Western Australia also received above-average rainfall, extending from the Pilbara through the interior to the central south coast and also in much of the South West Land Division.

An East Coast Low late in the month produced very heavy rainfall in coastal New South Wales, resulting in extensive damage and several daily and monthly rainfall records. Overall, it was New South Wales' 11th-wettest April on record and wettest April in 25 years. Please see the New South Wales monthly summary (or forthcoming Monthly Weather Review) for further detail. Heavy rainfall in northern agricultural and southern pastoral districts of South Australia around mid-month also set some records.


Area-average rainfall
Rank
(of 116)
Average
(mm)
Departure
from mean
Comment
Australia 60 27.1 −12%
Queensland 36 21.1 −50%
New South Wales 106 68.7 +47%
Victoria 81 59.6 +17%
Tasmania 5 40.9 −64% 5th lowest
South Australia 96 20.5 +26%
Western Australia 79 27.0 +29%
Northern Territory 29 7.7 −73%
Murray-Darling Basin 95 48.0 +26%

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 April 2015
Hottest day   41.5 °C at Borroloola Airport (NT) on 6 April
Coldest day   −1.0 °C at Mount Hotham (Vic.) on 19 April
Coldest night   −6.9 °C at Liawenee (Tas.) on 20 April
Warmest night   29.7 °C at Broome NTC AWS (NT) on 1 April
Wettest day 307.5 mm at Maitland Belmore Bridge (Hunter River) (NSW) on 22 April


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 Friday 1 May 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 May 2009; the main effect was that current and historical values for Tasmania were increased. Since April 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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