Melbourne Metropolitan Area and Environs in summer 2011-12:

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 16.3C (departure from normal 2.4C). 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 26.5C (departure from normal 1.2C). Total rainfall for the past summer (Dec 2011 to Feb 2012) was 167.2 mm, this being close to that usually recorded (normal 155.0 mm, percentage of normal received 108%).

Some 20 kilometres northwest of the Melbourne city centre, and more representative of the suburbs, is Melbourne Airport. Here, overnight minimum temperatures were just slightly warmer than those usually experienced and averaged 13.8C (departure from normal 0.5C). Daytime maximum temperatures were also slightly warmer than those usually experienced and averaged 26.2C (departure from normal 0.5C). Total rainfall for the past twelve months was 154.6 mm, this being slightly more than that usually recorded (normal 135.6 mm, percentage of normal received 114%).

One of the season's most significant events occurred on Christmas day, when there was an exceptionally severe hailstorm, which affected much of Melbourne's northern and eastern suburbs.

Some sites had their lowest summer temperature on record.

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Extremes in summer 2011-12
Hottest day 41.1 C at Avalon Airport on 2 Jan 2012
Warmest days on average 26.8 C at Viewbank (ARPANSA)
Coolest days on average 24.3 C at Cerberus
Coldest day 15.9 C at Cerberus on 4 Dec 2011
15.9 C at Melbourne Airport on 4 Dec 2011
Coldest night 3.0 C at Coldstream on 8 Feb 2012
Coolest nights on average 11.7 C at Coldstream
Warmest nights on average 16.3 C at Melbourne Regional Office
Warmest night 24.7 C at Melbourne Regional Office on 26 Feb 2012
Warmest on average overall 21.4 C at Melbourne Regional Office
Coolest on average overall 19.1 C at Coldstream
19.1 C at Cranbourne Botanic Gardens
Wettest overall 215.4 mm at Viewbank (ARPANSA)
Highest wind gust 100 km/h at Melbourne Airport on 25 Dec 2011

Record lowest summer temperature
Lowest temperature
in summer 2011-12 (C)
Previous coolest
for summer
Years of
record
Average for
summer
Melbourne Airport 3.5 on 5 Dec 2011 4.1 on 15 Dec 1986 42 13.2
Cranbourne Botanic Gardens 4.1 on 5 Dec 2011 5.2 on 1 Dec 1994 23 13.1



Highest summer mean daily minimum temperature for at least 10 years
Mean daily minimum
temperature
for summer 2011-12 (C)
Most recent summer
at least this warm
Years since
warmer
Average for
summer
Cerberus 14.3 14.5 in 2000 11 13.2



Summary statistics for summer 2011-12
Maximum temperatures
for summer
(C)
Minimum temperatures
for summer
(C)
Rainfall
for summer
(millimetres)
Mean for
summer
2011-12
Diff
from
average
Highest for
summer
2011-12
Mean for
summer
2011-12
Diff
from
average
Lowest for
summer
2011-12
Total for
summer
2011-12
Average
for
summer
Rank of
summer
2011-12
Fraction of
summer
average
Avalon Airport 25.7 +0.3 41.1 2 Jan 2012 14.0 +0.7 6.9 1 Dec 2011 103.6 95.0 average 109%
Cerberus 24.3 +0.6 39.5 2 Jan 2012 14.3 +1.1 4.9 5 Dec 2011 156.8 132.9 average 118%
Coldstream 26.5 -0.2 36.5 2 Jan 2012 11.7 +0.6 3.0 8 Feb 2012 203.2 158.9 high 128%
Cranbourne Botanic Gardens 24.7 -0.2 38.4 2 Jan 2012 13.3 +0.2 4.1 5 Dec 2011 164.3 175.7 average 94%
Essendon Airport 26.1 +0.7 39.0 2 Jan 2012 14.4 +1.4 4.7 5 Dec 2011 164.2 142.6 average 115%
Laverton RAAF 25.4 +0.5 39.5 2 Jan 2012 14.6 +1.3 5.8 6 Dec 2011 140.6 133.3 average 105%
Melbourne Airport 26.2 +0.5 39.2 2 Jan 2012 13.8 +0.6 3.5 5 Dec 2011 154.6 135.6 average 114%
Melbourne Regional Office 26.5 +1.2 40.0 2 Jan 2012 16.3 +2.4 8.6 5 Dec 2011 167.2 155.0 average 108%
Moorabbin Airport 25.5 +0.4 39.7 2 Jan 2012 14.4 +0.8 5.6 5 Dec 2011 132.8 151.9 average 87%
Scoresby Research Institute 26.2 +0.7 38.1 2 Jan 2012 13.5 +0.5 4.1 5 Dec 2011 200.4 184.6 average 109%
Viewbank (ARPANSA) 26.8 +0.1 38.8 2 Jan 2012 14.0 +0.2 5.0 5 Dec 2011 215.4 167.2 high 129%

Notes

A Seasonal 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 2 am on Thursday 1 March 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

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