Melbourne Metropolitan Area and Environs in April 2013:

 

Rainfall much less than 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 12.3C (departure from normal 1.5C). 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 warmer than those usually experienced and averaged 21.3C (departure from normal 1C). Total rainfall for the month was 27.2 mm, this being much less than that usually recorded (normal 57.1 mm, percentage of normal received 48%).

Some 20 kilometres northwest of the Melbourne city centre, Melbourne Airport, is typical of the Melbourne suburban area. Here, overnight minimum temperatures were near to those usually experienced and averaged 10.3C (departure from normal 0.2C). Daytime maximum temperatures were near to those usually experienced and averaged 20.5C (departure from normal 0.2C). Total rainfall for the month was 22.6 mm, this being less than that usually recorded (normal 43.1 mm, percentage of normal received 52%).

Records

Some sites had their lowest total April rainfall on record.

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


Extremes in April 2013
Hottest day 29.9 C at Avalon Airport on the 7th
Warmest days on average 21.3 C at Avalon Airport
21.3 C at Melbourne Regional Office
Coolest days on average 19.9 C at Cerberus
Coldest day 14.9 C at Viewbank on the 15th
Coldest night -0.8 C at Coldstream on the 21st
Coolest nights on average 7.5 C at Coldstream
Warmest nights on average 12.3 C at Melbourne Regional Office
Warmest night

19.3 C at Melbourne Regional Office

on the 13th

Warmest on average overall 16.8 C at Melbourne Regional Office
Coolest on average overall 14.3 C at Coldstream
Wettest overall 33.4 mm at Bundoora (Latrobe University)
Highest wind gust 67 km/h at Avalon Airport on the 27th

Record lowest total April rainfall
Total rainfall
for April 2013 (mm)
Previous driest
for April
Years of
record
Average for
April
Coldstream 14.4 18.8 in 2005 19 59.9

Lowest total April rainfall for at least 10 years
Total rainfall
for April 2013 (mm)
Most recent April
at least this dry
Years since
drier
Average for
April
Cerberus 18.4 18.0 in 1999 14 64.2
Laverton RAAF 11.4 9.4 in 1999 14 45.1



Summary statistics for April 2013
Maximum temperatures
for April
(C)
Minimum temperatures
for April
(C)
Rainfall
for April
(millimetres)
Mean for
April
2013
Diff
from
average
Highest for
April
2013
Mean for
April
2013
Diff
from
average
Lowest for
April
2013
Total for
April
2013
Average
for
April
Rank of
April
2013
Fraction of
April
average
Avalon Airport 21.3 +1.0 29.9 7th 10.0 +0.5 2.2 21st 10.2 36.0 low 28%
Bundoora (Latrobe University) 20.6 +0.1 27.2 12th 10.1 +0.4 3.0 21st 33.4 53.8 average 62%
Cerberus 19.9 +0.2 27.1 7th 9.8 -0.1 3.0 30th 18.4 64.2 v low 29%
Coldstream 21.0 +0.6 28.2 12th 7.5 +0.9 -0.8 21st 14.4 59.9 lowest 24%
Cranbourne Botanic Gardens 20.1 +0.3 27.9 7th 10.7 +0.5 6.0 4th 28.8 71.1 low 41%
Essendon Airport 20.8 +0.7 28.1 7th 10.6 +0.8 4.1 21st 18.8 54.1 low 35%
Laverton RAAF 20.4 +0.2 28.2 7th 10.4 +0.6 2.6 21st 11.4 45.1 v low 25%
Melbourne Airport 20.5 +0.2 27.7 7th 10.3 +0.2 5.0 30th 22.6 43.1 low 52%
Melbourne Regional Office 21.3 +1.0 28.2 6th 12.3 +1.5 6.9 21st 27.2 57.1 low 48%
Moorabbin Airport 20.3 +0.2 28.2 7th 10.3 -0.1 1.8 21st 18.0 62.3 v low 29%
Scoresby Research Institute 20.4 +0.4 27.4 12th 9.6 -0.5 3.5 30th 28.4 67.0 v low 42%
Viewbank 20.8 -0.6 28.2 12th 9.9 0.0 3.8 21st 21.4 55.7 low 38%

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 3 pm on Friday 3 May 2013. 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.

The ACORN-SAT dataset is being used for temperature area averages from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.


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