Australia in April 2012

In Brief

April rainfall was generally below average across the south of the Australian mainland, and above average for most of the Northern Territory and parts of the adjoining areas of the surrounding three states. Parts of the south-eastern seaboard and southern Tasmania received above-average rainfall. Maximum temperatures were generally above average across the south of Australia, and below average across the north and for parts of the Australian coast north of Victoria. Minimum temperatures followed a similar distribution, but warm anomalies in the south were more sparse and cool anomalies across the north were more widespread.


Temperatures

Averaged over Australia, April daytime temperatures were near average, with a national anomaly of +0.3°C. Tasmania recorded maximum temperatures 1.3°C above average, and Victoria and South Australia were 1.1°C and 1.0°C above average, respectively. For April minimum temperatures, Tasmania recorded a positive anomaly of +1.3°C, the fourth-highest on record. Apart from South Australia, which recorded a positive anomaly for minima of +0.3°C, the other states recorded cool anomalies generally on the order of −0.5°C. For Australia as a whole, April overnight temperatures were 0.4°C below average.

Maximum temperatures were above average across the south of Australia, covering the southern half of Western Australia, most of South Australia, parts of western New South Wales and a smaller part of the inland and north, western Victoria and the Gippsland coast, and all of Tasmania. Maximum temperatures were very much above average along the southern mainland coast and across Tasmania. Below-average maxima were restricted to parts of the north, corresponding with those areas receiving above-average rainfall; mostly in the Gulf Country and Northern Goldfields of Queensland and in an area extending from the eastern Kimberley in Western Australia to the western Barkly in the Northern Territory. Small areas of the very far north of the Top End and Cape York Peninsula recorded above-average maxima.

Overnight temperatures were below average for much of the mainland away from the southern and eastern coastline and through central Australia, where they were generally near-average to above average. Tasmania recorded very-much-above-average minima in the west of the state and above-average in the northeast. Below-average minima were recorded in central Western Australia, parts of the Kimberley and Arnhem Land in the Northern Territory and more broadly across the northern half of Queensland.

A cold outbreak was experienced in the southeast over the Easter break, as a passing cold front brought polar air north, producing snow in Tasmania and the Alps, followed by a high pressure system in the Bight bringing cold nights to the southeast, reaching as far north as southeast Queensland.


Areal average temperatures
  Maximum Temperature Minimum Temperature
Rank
(out of 63)
Anomaly*
(°C)
Comment Rank
(out of 63)
Anomaly*
(°C)
Comment
Australia 37 +0.3 20# −0.4
Queensland 22# −0.2 20 −0.6
New South Wales 41 +0.4 23 −0.6
Victoria 50 +1.1 32 −0.4
Tasmania 56 +1.3 60 +1.3 fourth highest
South Australia 49# +1.0 38 +0.3
Western Australia 39 +0.6 18 −0.4
Northern Territory 16 −0.6 19 −0.7

*Anomaly is the departure from the long-term (1961-1990) average.
#Indicates that the value is tied for that rank.


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

Rainfall

The conclusion of the 2011–12 La Niña during March saw an end to the wet conditions which had been commonplace across much of eastern Australia during recent months. Averaged over Australia, April rainfall was 41% below average, ranking as the 34th-driest in 113 years of record. April rainfall was above to very much above average for the Northern Territory excluding the Top End and south-eastern corner of the Territory, extending into the eastern Kimberley, and above-average in northern South Australia and parts of western and central Queensland extending towards the central coast. Southern Tasmania, scattered areas of southeast Queensland, parts of coastal New South Wales and East Gippsland in Victoria also received above-average rainfall.

Rainfall was below average across most of southern Western Australia and adjacent south-western South Australia, with a small part of the western Wheat Belt recording lowest-on-record April rainfall. Scattered small areas of lowest-on-record falls were also recorded throughout inland New South Wales and and extending into far southern Queensland. More generally, most of inland New South Wales, eastern South Australia, south-western Queensland, and much of western and central Victoria received below-average rainfall. Small areas around the north of Western Australia, the Northern Territory, and parts of coastal and northern Queensland recorded below- to very-much-below-average rainfall.

The Northern Territory was the only state or territory to record an above-average area-averaged total; the other states generally received rainfall 40 to 60% below average although Tasmanian rainfall was only 10% below average.


Area-average rainfall
Rank
(out of 113)
Average
(mm)
Departure
from mean*
Comment
Australia 34 18.1 −41%
Queensland 38 22.1 −47%
New South Wales 37 23.8 −49%
Victoria 30 29.5 −42%
Tasmania 47 101.8 −10%
South Australia 46 7.0 −57%
Western Australia 32 8.9 −57% lowest since 2001
Northern Territory 74 28.9 +4%
Murray-Darling Basin 24 14.1 −63%

*The mean is calculated for the 1961-1990 reference period.


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


Australian weather extremes in April 2012
Hottest day 42.0°C at Roebourne (WA) on 3 April
Coldest day −0.9°C at Mount Hotham (Vic) on 24 April
Coldest night −8.0°C at Charlotte Pass (NSW) on 11 April
Warmest night 28.5°C at Troughton Island (WA) on 21 April
Wettest day 183.4 mm at Gold Coast Seaway (Qld) on 29 April


Notes

The Seasonal 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.

This statement has been prepared based on information available at 12 noon EST on Tuesday 1 May 2012. 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.

In the tables, fractional ranks denote tied values.

A new area-averaging method was adopted for rainfall in May 2009. Current and historical totals for Tasmania are substantially higher than under the old scheme, but differences for other states, and nationally, are negligible. The rankings and departures from mean shown here use the new method.


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