Melbourne Metropolitan Area and Environs in October 2011:

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 11.4C (departure from normal 1.9C). That the overnight temperatures in Melbourne are higher than those in most surrounding localities - to illustrate, overnight temperatures at Melbourne Airport averaged 9.0C - 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 20.8C (departure from normal 1.1C). Total rainfall for the month was 64.2 mm, this being close to that usually recorded  (normal 66.4 mm, percentage of normal received 97%).

As is typical of seasons when we have a La Nia event over the Pacific, Victoria's weather was influenced by easterly flow, as a consequence of a persistence of anticyclones over higher latitudes - pressures were as much as 10 hPa above normal to the south of Tasmania.This resulted in more humid and slightly warmer weather than usual.

Rainfall

The wettest overall was 104.7 mm at Cranbourne Botanic Gardens.

Temperature

Maximum temperature

The hottest day was 31.7 C at Avalon Airport on the 20th.

The warmest days on average were 20.8 C at Melbourne Regional Office.

The coolest days on average were 19.1 C at Cerberus.

The coldest day was 11.8 C at Melbourne Airport on the 1st.

Minimum temperature

The coldest night was 0.9 C at Coldstream on the 3rd.

The coolest nights on average were 8.1 C at Coldstream.

The warmest nights on average were 11.4 C at Melbourne Regional Office.

The warmest night was 21.0 C at Moorabbin Airport on the 20th.

Some sites had their warmest October night (highest daily minimum temperature) on record.

Some sites had their highest October mean daily minimum temperature on record.

Some sites had their highest October mean daily minimum temperature for at least 10 years.

Wind

The strongest wind gust was 80 km/h at Melbourne Airport on the 28th.

Further information

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Extremes in October 2011
Hottest day 31.7 C at Avalon Airport on the 20th
Warmest days on average 20.8 C at Melbourne Regional Office
Coolest days on average 19.1 C at Cerberus
Coldest day 11.8 C at Melbourne Airport on the 1st
Coldest night 0.9 C at Coldstream on the 3rd
Coolest nights on average 8.1 C at Coldstream
Warmest nights on average 11.4 C at Melbourne Regional Office
Warmest night 21.0 C at Moorabbin Airport on the 20th
Wettest overall 104.7 mm at Cranbourne Botanic Gardens
Highest wind gust 80 km/h at Melbourne Airport on the 28th

Record highest October daily minimum temperature
Highest daily minimum
temperature
in October 2011 (C)
Previous highest
for October
Years of
record
Average for
October
Avalon Airport 19.5 on the 20th 18.5 on the 16th in 1996 17 7.8



Record highest October mean daily minimum temperature
Mean daily minimum
temperature
for October 2011 (C)
Previous highest
for October
Years of
record
Average for
October
Cerberus 9.9 9.5 in 2005 19 8.6
Coldstream 8.1 = 8.1 in 2005 17 6.4

Highest October mean daily minimum temperature for at least 10 years
Mean daily minimum
temperature
for October 2011 (C)
Most recent October
this high or higher
Years since
higher
Average for
October
Laverton RAAF 9.4 =9.4 in 1977 34 8.2
Avalon Airport 8.9 9.3 in 1999 12 7.8



Summary statistics for October 2011
Maximum temperatures
for October
(C)
Minimum temperatures
for October
(C)
Rainfall
for October
(millimetres)
Mean for
October
2011
Diff
from
average
Highest for
October
2011
Mean for
October
2011
Diff
from
average
Lowest for
October
2011
Total for
October
2011
Average
for
October
Rank of
October
2011
Fraction of
October
average
Avalon Airport 20.2 +0.4 31.7 20th 8.9 +1.1 1.9 18th 85.2 51.0 high 167%
Bundoora (Latrobe University) 20.1 +0.6 29.1 23rd 9.2 +0.6 2.0 3rd 78.5 65.6 average 120%
Cerberus 19.1 +0.9 29.1 20th 9.9 +1.3 3.6 4th 79.6 69.6 average 114%
Coldstream 20.4 +1.1 28.0 20th 8.1 +1.7 0.9 3rd 91.6 67.5 high 136%
Cranbourne Botanic Gardens 19.6 +0.9 29.0 20th 9.6 +0.9 4.3 13th 104.7 80.1 average 131%
Essendon Airport 19.9 +0.8 29.2 23rd 9.6 +1.5 2.6 3rd 68.2 61.3 average 111%
Laverton RAAF 19.9 +0.7 30.0 20th 9.4 +1.2 1.5 3rd 60.0 57.4 average 105%
Melbourne Airport 19.8 +0.6 29.1 23rd 9.0 +0.6 2.5 3rd 71.0 55.3 high 128%
Melbourne Regional Office 20.8 +1.1 30.3 23rd 11.4 +1.9 5.6 3rd 64.2 66.4 average 97%
Moorabbin Airport 19.7 +0.6 29.2 23rd 10.3 +1.1 3.7 3rd 77.4 71.1 average 109%
Scoresby Research Institute 20.0 +1.1 28.9 20th 9.3 +0.5 1.5 3rd 76.6 85.7 average 89%
Viewbank (ARPANSA) 20.3 +0.2 28.7 23rd 9.4 +0.7 2.3 3rd 82.2 68.2 average 121%

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 10 am on Wednesday 2 November 2011. 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