Monday, 30 April 2007 - Monthly Climate Summary for Victoria - Product code IDCKGC16R0
Finally, Victoria received useful rainfalls over a large swathe of the State. The exception was in the Central District and West Gippsland, which didn't have the benefit of the last weekend's downpour. Temperatures were above average. The reason for the rainfall is that, firstly, temperatures in the ocean off SW Western Australia have been below normal, allowing more active jet streams than usual to form as a result of the "Indian Ocean Dipole". Over the far eastern Pacific, cold waters are almost suggestive of a possible La Niņa.
In Melbourne, the average maximum temperature was 22.8 deg C (normal 20.6 deg C), whilst the average minimum was 12.3 deg C (normal 11.7 deg C). 22.8 mm of rain fell (normal 52.7 mm).
Falls of over 100 mm were recorded at some places, mostly towards the end of the month, especially in the northwest and far east of the State.
The heaviest recorded fall, overall, was 157.6 mm at Gabo Island Lighthouse. The driest overall was 13.8 mm at Omeo Comparison. The wettest single day 62.8 mm at Grampians (Mount William) on the 28th.
Some sites had their highest total April rainfall for at least 20 years.
Some sites had their lowest total April rainfall on record.
Some sites had their lowest total April rainfall for at least 20 years.
Maximum temperature were more than 2 deg C above normal in the northwest, and around 1 deg C above average elsewhere. Minimum temperatures were mostly near average, but slightly above average in the northwest, and slightly below average in the east.
The hottest day was 32.0°C at Horsham Aerodrome on the 14th. The warmest days on average were 25.8°C at Mildura Airport, followed by 25.8°C at Ouyen (Post Office). The coolest days on average were 9.7°C at Mt Hotham. The coldest day was 5.0°C at Mt Baw Baw on the 23rd.
The coldest night was −2.4°C at Mt Hotham Airport on the 7th. The coolest nights on average were 3.6°C at Mt Hotham. The warmest nights on average were 14.6°C at Gabo Island Lighthouse, followed by 14.6°C at Wilsons Promontory Lighthouse. The warmest night was 18.1°C at Walpeup Research on the 11th.
Some sites had their highest April mean daily minimum temperature for at least 20 years.
The strongest wind gust was 104 km/h at Wilsons Promontory Lighthouse on the 28th.
There were several days with thunderstorms, some with hail, during the month.
Blocking highs prevailed during the first two weeks. However, by the end of April, synoptic situations had become typical for late autumn, with westerlies and embedded fronts racing across the southern ocean.
|32.0°C at Horsham Aerodrome on the 14th|
|Warmest days on average|
Highest mean daily maximum temperature
25.8°C at Mildura Airport|
25.8°C at Ouyen (Post Office)
|Coolest days on average|
Lowest mean daily maximum temperature
|9.7°C at Mt Hotham|
Lowest daily maximum temperature
|5.0°C at Mt Baw Baw on the 23rd|
|−2.4°C at Mt Hotham Airport on the 7th|
|Coolest nights on average|
Lowest mean daily minimum temperature
|3.6°C at Mt Hotham|
|Warmest nights on average|
Highest mean daily minimum temperature
14.6°C at Gabo Island Lighthouse|
14.6°C at Wilsons Promontory Lighthouse
Highest daily minimum temperature
|18.1°C at Walpeup Research on the 11th|
Highest total rainfall
|157.6 mm at Gabo Island Lighthouse|
Lowest total rainfall
|13.8 mm at Omeo Comparison|
Highest daily rainfall
|62.8 mm at Grampians (Mount William) on the 28th|
|Highest wind gust||104 km/h at Wilsons Promontory Lighthouse on the 28th|
|Record lowest total April rainfall|
for April 2007 (mm)
|Scoresby Research Institute||18.4||18.7||in 1958||55||68.6|
|Noojee (Slivar)||16.2||24.8||in 1993||26|
|Highest total April rainfall for at least 20 years|
for April 2007 (mm)
Most recent higher
|Walpeup Research||76.6||100.9||in 1970||37||26.5|
|Ouyen (Post Office)||82.3||82.6||in 1971||36||26.6|
|Horsham (Polkemmet)||67.4||104.8||in 1974||33||30.3|
|Lowest total April rainfall for at least 20 years|
for April 2007 (mm)
Most recent lower
|Wilsons Promontory Lighthouse||24.6||11.8||in 1962||45||84.1|
|Moorabbin Airport||16.8||8.2||in 1963||42||61.6|
|Highest April mean daily minimum temperature for at least 20 years|
Mean daily minimum
for April 2007 (°C)
Most recent higher
|Cape Otway Lighthouse||13.2||13.3||in 1919||88||11.9|
|Mildura Airport||11.6||12.3||in 1980||27||10.5|
|Casterton Showgrounds||9.8||10.4||in 1980||22||9.1|
|Horsham (Polkemmet)||9.1||9.9||in 1980||22||8.8|
In the following table, certain key sites have been highlighted to make them easier to identify.
|Summary statistics for April 2007|
|North Mallee (district 76)|
|Walpeup Research||25.2||+2.2||31.3||11th||12.0||+1.7||7.0||6th||76.6||26.5||very high||289%|
|South Mallee (district 77)|
|Swan Hill Aerodrome||24.9||31.3||14th||9.7||7.2||4th||51.8|
|North Wimmera (district 78)|
|South Wimmera (district 79)|
|Lower North (district 80)|
|Upper North (district 81)|
|Tatura Inst Sustainable Ag||23.8||+2.4||29.1||14th||8.7||+0.3||4.7||20th||31.4||42.0||normal||75%|
|Lower Northeast (district 82)|
|Upper Northeast (district 83)|
|Mt Hotham Airport||15.6||20.4||13th||3.7||−2.4||7th||25.4|
|Omeo Comparison||25.4||15th||5.7||+0.6||0.3||9th||13.8||50.2||very low||27%|
|East Gippsland (district 84)|
|Gabo Island Lighthouse||20.1||+1.0||23.0||15th||14.6||+0.7||12.2||26th||157.6||91.6||high||172%|
|Mt Nowa Nowa||19.3||27.7||14th||11.6||8.2||6th||145.0|
|West Gippsland (district 85)|
|East Sale Airport||21.0||+0.6||28.0||14th||8.8||−0.1||4.3||7th||53.2||52.9||normal||101%|
|Mt Baw Baw||11.4||16.2||14th||5.1||−0.3||6th||18.4|
|Wilsons Promontory Lighthouse||18.2||+0.9||23.6||10th||14.6||+1.5||12.7||5th||24.6||84.1||very low||29%|
|East Central (district 86)|
|Cranbourne Botanic Gardens||21.8||28.0||10th||10.2||7.4||26th||23.0|
|Melbourne Regional Office||22.8||+2.2||29.3||10th||12.3||+0.6||8.3||26th||22.8||52.7||low||43%|
|Moorabbin Airport||22.2||+2.0||29.6||14th||10.0||−0.8||5.3||25th||16.8||61.6||very low||27%|
|Phillip Island Penguin Reserve||21.0||27.3||10th||10.3||3.5||12th||22.2|
|Scoresby Research Institute||22.3||+2.4||28.1||10th||9.2||−1.4||3.4||26th||18.4||68.6||lowest||27%|
|West Central (district 87)|
|North Central (district 88)|
|Eildon Fire Tower||20.8||25.8||13th||10.5||6.8||4th||18.0|
|Western Plains (district 89)|
|West Coast (district 90)|
|Cape Nelson Lighthouse||19.1||28.8||9th||13.5||10.8||20th||52.8|
|Cape Otway Lighthouse||18.3||+0.5||26.4||10th||13.2||+1.3||8.2||12th||45.8||75.1||normal||61%|
|Port Fairy AWS||20.8||30.7||14th||12.0||6.9||20th||46.6|
|Warrnambool Airport Ndb||21.5||30.7||14th||9.7||2.7||12th||50.2|
This statement has been prepared based on information available at 11 am on Monday 30 April 2007. Some checks have been made on the data, but it is possible that results will change as new information becomes available.
Normals are long-term means based on observations from
the years 1961 to 1990.
They are not shown for sites with less than 20 years of record in that time, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of "normal" rain.
The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
(very low rainfall is in decile 1, low in decile 2 or 3,
normal in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of normal shows how much rain has fallen this time as a percentage of the long-term mean.