Tuesday, 29 September 2009 - Monthly Climate Summary for Victoria - Product code IDCKGC26R0

Victoria during September 2009
Above normal rainfall in many areas

September 2009 saw above normal rainfall across much of Victoria, in spite of the tropical Pacific Ocean temperatures remaining warmer than average in all of the key El Niņo monitoring regions and continuing to exceed thresholds considered typical of an El Niņo event. The reason for the above normal rainfall is that unlike previous El Niņo events, conditions are also warmer than average in the Coral Sea, off Australia's northern coasts and in the far western Tropical Pacific, and the Southern Oscillation Index is slightly positive (during typical El Niņo events, the Southern Oscillation Index is negative).

Another region of Sea Surface Temperature variability that impacts on Australian climate is that of the Indian Ocean. One mode of variability that appears to affect Australian rainfall, particularly the southeast of the country, is the Indian Ocean Dipole. The Indian Ocean Dipole referred to here is defined by an index that is the difference between Sea Surface Temperature in the western and eastern tropical Indian Oceans. At present, the eastern Indian Ocean is warmer than the western Indian Ocean. This encourages the formation of rain-bearing northwest cloud bands ahead of cold fronts approaching Victoria.

Both overnight and daytime temperatures averaged above normal throughout the State, continuing the trend of recent months. The last week of the month saw above normal sea surface temperatures stretching across the entire equatorial Indian and Pacific Oceans, including Indonesian waters and the Tasman Sea. The ongoing warmth may be attributed to these above normal sea surface temperatures. September 12 saw an extraordinary burst of heat in Victoria, as strong NW winds, ahead of an approaching cold front, drove hot air from inland Australia across the State. Several centres registered record September temperatures during this event. 

Synoptic Summary

The month began with an anticyclone of 1025 hPa over NSW and light westerly flow across Victoria. the high moved over the Tasman Sea and northerly winds strengthened ahead of an approaching front on the 3rd. the frontal system retreated and a new anticyclone of 1021 hPa had formed over NSW by the 5th. the settled weather was short-lived as another front approached and passed across the State on the 7th. A low formed on this front and developed as it moved over the Tasman Sea on the 9th, but a new high pressure system soon developed over NSW in its wake. This high retreated to the NE to be located over NSW/QLD border and directed extremely warm NW winds across Victoria on the 12th, leading to many September maximum temperature records tumbling. A front crossed the State early on the 13th and a high of 1023 hPa then formed over southern NSW on the 14th. This high moved eastward and was followed by a friontal passage on the 17th, with a small wave low  appearing over the Tasman Sea on the 18th. The 19th saw another frontal passage, prior to temporary stabilsation on the 20th, before a very intense cyclonic system moved across Victoria on the 22nd and 23rd. Some stabilisation occurred on the 24th but a new front moved through Victoria on the 25th, and this was followed by development over the Tasman Sea on the 26th and 27th. the month conclude with an anticyclone once again exerting its stabilising influence across Victoria.

An archive of previous monthly summaries for Victoria is also available, as are summaries for other states and many other climate summaries and diagnostics.

Further information

Dr Harvey Stern
Climate Meteorologist
Victoria Climate Services Centre
Bureau of Meteorology
Phone (03) 9669 4956
Email climate.vic@bom.gov.au

Records


Record highest September temperature
Highest temperature
in September 2009 (°C)
Previous highest
for September
Years of
record
Average for September
Laverton RAAF 31.2 on the 12th 31.0 on the 26th in 1987 66 16.9
Gabo Island Lighthouse 30.6 on the 12th 30.5 on the 16th in 1996 53 15.7
Kerang 34.0 on the 12th = 34.0 on the 27th in 2008 47 18.8
Kyabram DPI 32.2 on the 12th = 32.2 on the 27th in 2008 44 17.2
Castlemaine Prison 28.4 on the 12th 28.0 on the 27th in 1987 43 15.6
Essendon Airport 30.3 on the 12th 28.9 on the 19th in 2006 40 16.6
Melbourne Airport 30.2 on the 12th 29.0 on the 27th in 2008 40 16.5
Bundoora (Latrobe University) 29.2 on the 12th 29.0 on the 26th in 1987 31 16.8
Sheoaks 28.1 on the 12th = 28.1 on the 19th in 2006 20 15.3


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Summaries

This table is very wide and may not fit if printed.

Summary statistics for September 2009
Maximum temperatures
for September
(°C)
Minimum temperatures
for September
(°C)
Rainfall
for September
(millimetres)
Mean for
September
2009
Diff
from
average
Highest for
September
2009
Mean for
September
2009
Diff
from
average
Lowest for
September
2009
Total for
September
2009
Average
for
September
Rank of
September
2009
Fraction of
September
average
North Mallee (district 76)
Mildura Airport 22.1 +1.7 34.0 12th 7.9 +0.5 2.4 10th 28.6 27.0 average 106%
Ouyen 21.5 +1.3 34.4 12th 7.3 +0.6 3.5 15th 84.0 32.6 very high 258%
Walpeup Research 21.0 +1.5 34.6 12th 7.4 +0.5 2.0 9th 73.6 31.7 very high 232%
South Mallee (district 77)
Hopetoun Airport 20.4   34.6 12th 4.8   -1.4 14th 30.6
Swan Hill Aerodrome 20.9 +0.7 34.0 12th 5.7 -0.4 0.6 15th 41.8 27.2 high 154%
North Wimmera (district 78)
Nhill Aerodrome 18.4   32.3 12th 6.1   1.3 14th 46.0
Warracknabeal Museum 19.0 +0.9 33.0 12th 6.1 +0.2 1.0 15th 51.8 42.0 average 123%
South Wimmera (district 79)
Edenhope Airport 16.9   27.8 12th 6.6   1.2 10th 62.6
Grampians 8.3   20.6 12th 2.0   -1.6 27th 144.4
Horsham Aerodrome 17.6 -0.6 30.8 12th 4.4 0.0 -0.7 14th 83.0 38.9 very high 213%
Horsham Polkemmet Rd 17.8 +0.2 31.2 12th 4.7 -0.8 -1.4 14th 65.2 46.2 high 141%
Kanagulk 16.6   28.4 12th 5.7   0.4 14th 45.4
Longerenong 17.2 -0.1 29.7 12th 4.7 -0.4 -1.0 14th 71.6 40.7 high 176%
Pyrenees 11.3   23.4 12th 4.2   0.1 27th 128.0
Stawell Aerodrome 16.5 -0.2 29.3 12th 6.5 +0.6 1.6 14th 79.6 56.0 high 142%
Lower North (district 80)
Charlton 18.8   32.3 12th 5.5   -0.7 10th 49.6
Echuca Aerodrome 19.7 +1.4 32.2 12th 5.3 -1.0 0.8 15th 30.0 39.2 average 77%
Kerang 20.6 +1.6 34.0 12th 6.3 -0.3 1.5 15th 47.6 35.6 high 134%
Kyabram DPI 19.4 +2.0 32.2 12th 4.8 -0.5 -0.6 14th 30.8 42.7 average 72%
Upper North (district 81)
Bendigo Airport 17.3 +0.6 30.4 12th 4.1 -0.2 -1.0 15th 53.4 48.5 average 110%
Shepparton Airport 18.7 +0.5 31.5 12th 4.4 -1.0 -1.5 5th 44.4 38.2 average 116%
Tatura Inst Sustainable Ag 18.5 +1.1 31.4 12th 4.5 -1.0 -1.4 15th 42.4 43.6 average 97%
Yarrawonga 19.2 +0.8 31.3 12th 4.8 -0.4 -1.2 15th 39.8 44.9 average 89%
Lower Northeast (district 82)
Benalla Airport 17.3   26.1 12th 4.6   -0.9 5th 62.5
Corryong Airport 17.5   26.0 13th 3.7   -1.3 6th 89.8
Dartmouth Reservoir 17.1 +0.5 24.2 12th 4.3 -0.2 -0.5 6th 137.4 106.0 high 130%
Rutherglen Research 17.7 +0.6 26.8 12th 4.3 +0.1 -1.4 29th 43.0 54.6 average 79%
Strathbogie 13.8 -0.4 23.0 12th 4.1 +0.4 -2.1 15th 98.8 95.8 average 103%
Wangaratta Aero 17.4 0.0 25.1 12th 4.2 -0.5 -0.8 15th 53.6 56.6 average 95%
Upper Northeast (district 83)
Dinner Plain 11.5   19.1 16th 0.6   -5.0 14th 103.2 84.8 high 122%
Edi Upper 16.1 -0.1 24.2 12th 5.6 +0.1 1.5 2nd 117.4 106.3 average 110%
Falls Creek 5.1 +0.4 11.9 16th -0.9 0.0 -5.8 27th 140.2 125.2 average 112%
Mount Buller 5.2 +0.3 13.0 16th -1.0 -0.3 -5.0 27th 237.6 148.0 high 161%
Mount Hotham 3.5 +0.1 10.7 16th -1.8 -0.3 -6.2 27th 177.6 129.0 high 138%
Omeo 15.8   22.3 16th 3.6   -2.9 2nd 80.6
Omeo Comparison 15.6 +0.5 22.0 16th     -2.8 6th 83.8 61.5 high 136%
East Gippsland (district 84)
Combienbar AWS 17.1 +1.4 25.6 12th 6.8 +0.5 2.3 27th 79.0 70.5 average 112%
Gabo Island Lighthouse 17.7 +1.8 30.6 12th 10.5 +0.8 7.2 16th 69.2 72.8 average 95%
Gelantipy 14.9 +1.1 22.8 17th 4.6 +0.2 -1.0 5th 87.8 57.8 high 152%
Lakes Entrance 18.7   29.6 12th 8.0   1.2 28th 66.4
Mallacoota 18.4 +1.0 31.0 12th 9.0 +1.0 5.3 30th 127.0 83.3 high 152%
Mount Nowa Nowa 17.9 +1.0 27.6 12th 8.0 +0.1 4.9 27th 73.6 58.9 high 125%
Orbost 19.4   28.9 12th 7.7   3.7 6th 105.2
Orbost 19.9 +2.1 29.9 12th 6.6 +0.3 1.4 5th 93.2 71.4 high 131%
Point Hicks 18.2 +1.7 29.9 12th 10.1 +0.6 5.2 27th 102.0 76.7 high 133%
West Gippsland (district 85)
Bairnsdale Airport 19.7 +2.2 29.7 12th 6.6 +0.8 0.6 5th 51.2 54.7 average 94%
East Sale Airport 18.8 +1.8 28.3 12th 5.7 +0.1 -0.4 2nd 64.0 52.2 high 123%
Morwell 17.7 +0.8 28.6 12th 6.2 +0.4 -0.8 5th 87.8 78.4 average 112%
Mount Baw Baw 6.0 +0.3 14.1 16th -0.3 -0.2 -3.8 27th 376.4
Mount Moornapa 17.0 +0.9 28.9 12th 7.2 +0.4 3.9 5th 85.2 54.2 high 157%
Noojee 15.8 +0.4 25.0 12th 5.4 +0.3 0.1 5th 203.2 125.9 high 161%
Pound Creek 16.9   27.1 12th 7.9   0.2 15th 85.4
Wilsons Promontory Lighthouse 15.8 +1.6 28.0 12th 10.2 +1.2 6.4 27th 142.0 98.8 high 144%
Yarram Airport 17.9   28.0 12th 6.9   0.6 11th 69.4
East Central (district 86)
Bundoora 17.8 +1.0 29.2 12th 8.0 +0.8 3.9 14th 90.4 59.3 high 152%
Cerberus 17.1 +0.9 27.6 12th 8.1 +0.7 1.3 15th 90.6 66.7 high 136%
Coldstream 16.9 -0.3 26.2 12th 6.0 +0.6 -0.6 15th 135.2 69.3 very high 195%
Coldstream Comparison 17.1   26.4 12th 5.9   -0.6 15th 135.2
Cranbourne Botanic Gardens 17.3 +0.9 27.5 12th 8.4 +0.7 4.0 15th 106.0 86.9 average 122%
Essendon Airport 18.1 +1.5 30.3 12th 8.2 +1.7 2.0 15th 56.4 50.9 average 111%
Ferny Creek 12.9 +0.3 23.4 12th 6.2 +0.2 2.8 27th 190.0 91.5 very high 208%
Frankston AWS 16.3 +0.9 26.7 12th 10.4 +1.2 6.9 15th
Melbourne Airport 17.9 +1.4 30.2 12th 7.8 +0.8 3.1 15th 54.0 46.2 average 117%
Melbourne Regional Office 18.6 +1.4 29.9 12th 9.9 +2.0 5.5 15th 67.4 58.0 high 116%
Moorabbin Airport 17.7 +0.9 29.3 12th 8.9 +1.0 3.0 16th 73.6 65.7 average 112%
Rhyll 16.4 +0.5 23.8 12th 10.0 +0.7 7.1 27th 76.0 66.8 average 114%
Scoresby Research Institute 17.3 +0.9 27.8 12th 8.2 +0.7 2.7 15th 117.8 85.1 high 138%
Viewbank 17.9   29.0 12th 8.1   2.2 15th 108.0 53.8 very high 201%
Wallan 12.9 -0.2 24.3 12th 5.6 0.0 1.3 5th 91.8 54.5 high 168%
Wonthaggi 17.3 +1.3 27.2 12th 8.5 +0.9 3.5 15th 92.5 89.4 average 103%
West Central (district 87)
Avalon Airport 18.6 +0.9 30.8 12th 7.2 +0.6 1.2 15th 70.6 45.8 high 154%
Grovedale 17.2 +0.6 29.1 12th 6.8 +0.3 1.5 15th 54.0 49.5 average 109%
Laverton RAAF 18.7 +1.7 31.2 12th 8.1 +1.5 3.0 15th 58.8 49.7 average 118%
Sheoaks 16.1 +0.8 28.1 12th 6.7 +0.6 1.2 15th 64.4 49.0 high 131%
North Central (district 88)
Castlemaine Prison 15.8 +0.1 28.4 12th 5.7 +0.8 -0.4 14th 85.6 60.6 high 141%
Eildon Fire Tower 13.0 -0.5 22.2 12th 5.6 -0.2 1.6 27th 91.0 62.1 high 147%
Lake Eildon 16.9 +0.5 26.1 12th 6.0 +0.5 0.2 29th 112.0 81.8 high 137%
Mangalore Airport 17.3 +0.5 29.3 12th 4.9 -0.4 -0.9 29th 38.8 55.7 average 70%
Maryborough 16.9 +0.2 29.9 12th 5.8 +0.4 0.6 15th 74.8 51.6 high 145%
Redesdale 15.9 -0.2 28.5 12th 4.1 -0.1 -0.7 5th 80.0 53.5 high 150%
Western Plains (district 89)
Ararat Prison 15.9 +0.9 27.9 12th 5.8 +0.8 -0.8 14th 84.8 62.5 high 136%
Ballarat Aerodrome 14.3 +0.5 26.2 12th 4.8 0.0 -0.5 15th 89.4 71.7 high 125%
Westmere 15.7   25.7 12th 5.3   0.0 15th 78.2
West Coast (district 90)
Aireys Inlet 16.9 +0.9 27.0 12th 8.3 +0.3 5.7 5th 79.2 59.6 high 133%
Cape Nelson Lighthouse 16.2 +0.4 26.9 12th 9.4 0.0 6.7 29th 97.0 78.1 high 124%
Cape Otway Lighthouse 15.3 +0.1 26.2 12th 9.1 +0.6 5.7 27th 107.2 90.3 high 119%
Casterton 16.1   26.5 12th 6.5   1.5 15th 74.4
Casterton Showgrounds 17.0 +0.6 27.0 12th 6.7 +0.3 -0.2 15th 87.6 73.8 average 119%
Colac 14.6   24.2 12th 6.8   3.5 14th 73.4 50.7 high 145%
Dartmoor 16.4   26.5 12th 7.1   1.0 15th 99.0
Hamilton Airport 15.6 +0.4 25.5 12th 6.2 +0.5 1.4 14th 73.8 70.7 average 104%
Mortlake Racecourse 15.8 +0.2 25.4 12th 6.3 +0.8 1.5 15th 68.8 57.7 high 119%
Port Fairy AWS 16.9 +0.3 26.0 12th 8.1 -0.1 4.4 15th 91.4 69.7 very high 131%
Portland 15.4 +0.2 25.8 12th 7.7 +0.2 3.4 15th 101.8 87.1 average 117%
Warrnambool Airport NDB 16.0 0.0 25.0 12th 7.0 +0.5 2.9 15th 83.6 69.8 high 120%
Weeaproinah 12.1 +0.5 22.1 12th 5.8 +0.3 2.6 26th 199.8 199.9 average 100%
 

Notes

This statement has been prepared based on information available at 3pm on Friday 2 October 2009. 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

Dr Harvey Stern
Climate Meteorologist
Victoria Climate Services Centre
Bureau of Meteorology
Phone (03) 9669 4956
Email climate.vic@bom.gov.au