Melbourne Metropolitan Area and Environs in April 2012:

Rainfall close to that usually received.

Located in the Central District at the head of Port Phillip Bay, Melbourne is Victoria's State Capital. Here, overnight minimum temperatures were much warmer than those usually experienced and averaged 12.0C (departure from normal 1.2C).

That the overnight temperatures in Melbourne are higher than those in most surrounding localities is a consequence of the city being under the influence of the effect of urbanisation (cities are usually warmer than their rural surroundings, especially at night, because of heat stored in bricks and concrete and trapped between close-packed buildings).

Daytime maximum temperatures were much warmer than those usually experienced and averaged 21.9C (departure from normal 1.6C).

Total rainfall for the month was 49.6 mm, this being close to that usually recorded (normal 57.3 mm, percentage of normal received 87%).

Across the Melbourne Metropolitan Area taken as a whole, overnight minimum temperatures were near to those usually experienced (average departure from normal 0.2C). Daytime maximum temperatures at most localities were warmer than those registered in the past (average departure from normal 1.2C). Total rainfall for the month was generally close to that usually recorded (average percentage of normal received 93.3%).

Some sites had their highest total April rainfall for at least 10 years.

Other phenomena

There were thunderstorms in some parts during the afternoons and evenings of the 2nd, 6th, 22nd and 23rd, and also some notable fog areas on the morning of the 21st.

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Extremes in April 2012
Hottest day 31.5 C at Avalon Airport on the 6th
Warmest days on average 21.9 C at Melbourne Regional Office
Coolest days on average 20.4 C at Cerberus
Coldest day 11.6 C at Coldstream on the 24th
Coldest night 1.2 C at Coldstream on the 12th
1.2 C at Coldstream on the 30th
Coolest nights on average 7.0 C at Coldstream
Warmest nights on average 12.0 C at Melbourne Regional Office
Warmest night 17.7 C at Bundoora (Latrobe University) on the 3rd
Warmest on average overall 17.0 C at Melbourne Regional Office
Coolest on average overall 14.1 C at Coldstream
Wettest overall 117.0 mm at Scoresby Research Institute
Highest wind gust 89 km/h at Avalon Airport on the 6th

Highest total April rainfall for at least 10 years
Total rainfall
for April 2012 (mm)
Most recent April
at least this wet
Years since
wetter
Average for
April
Scoresby Research Institute 117.0 131.4 in 1965* 43 67.6

* note: there are gaps in the historical record at this site, so it is possible a higher value has gone unreported.




Summary statistics for April 2012
Maximum temperatures
for April
(C)
Minimum temperatures
for April
(C)
Rainfall
for April
(millimetres)
Mean for
April
2012
Diff
from
average
Highest for
April
2012
Mean for
April
2012
Diff
from
average
Lowest for
April
2012
Total for
April
2012
Average
for
April
Rank of
April
2012
Fraction of
April
average
Avalon Airport 21.6 +1.4 31.5 6th 9.8 +0.3 3.6 30th 30.2 36.8 average 82%
Bundoora (Latrobe University) 21.5 +1.0 27.5 6th 10.2 +0.5 5.0 12th 52.2 54.4 average 96%
Cerberus 20.4 +0.7 29.3 6th 10.7 +0.8 3.6 30th 64.8 66.4 average 98%
Coldstream 21.3 +1.0 28.3 6th 7.0 +0.4 1.2 12th 81.6 62.4 high 131%
Cranbourne Botanic Gardens 20.6 +0.8 30.2 6th 10.4 +0.2 4.5 30th 96.7 73.1 high 132%
Essendon Airport 21.4 +1.4 28.7 6th 10.3 +0.5 4.2 30th 32.2 54.6 low 59%
Laverton RAAF 21.3 +1.1 30.0 6th 9.6 -0.2 3.0 30th 38.8 45.6 average 85%
Melbourne Airport 21.0 +0.7 28.0 6th 9.9 -0.3 3.8 30th 34.4 43.6 average 79%
Melbourne Regional Office 21.9 +1.6 28.5 6th 12.0 +1.2 6.2 30th 49.6 57.3 average 87%
Moorabbin Airport 21.0 +0.9 29.7 6th 10.8 +0.4 3.0 30th 67.4 63.1 average 107%
Scoresby Research Institute 21.2 +1.3 28.4 6th 10.0 -0.1 3.7 30th 117.0 67.6 v high 173%
Viewbank 21.7 +0.3 29.1 6th 9.8 -0.2 3.6 30th 59.4 58.4 average 102%

Notes

A Monthly Climate Summary is prepared to list the main features of the weather in Melbourne Metropolitan Area and Environs 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.

This statement has been prepared based on information available at 1 pm 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.

Averages are long-term means based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Further information

Media
(03) 9669 4057
Enquiries