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Wednesday, 1 June 2011 - Seasonal Climate Summary for Sydney - Greater Sydney - Product code IDCKGC25L0
Sydney Observatory Hill recorded 533.4 mm of rain during Autumn, well above the historical average of 376.8 mm and the wettest Autumn since 672.8 mm fell in 2003. All three months during the season had above average rainfall, with both March and April the wettest in more than ten years.
The most significant rainfall event occurred during March as a complex low pressure system developed in a trough off the coast, with daily totals of up to 178 mm at St Ives on the 20th and record-breaking daily falls in the Northern Beaches area. Rainfall reached 99.4 mm at Observatory Hill, the wettest Autumn day since May 1998. Rainfall over 50 mm was also recorded on April 16 and May 31, above the historical average of 1-2 50 mm days and the largest number of heavy days since Autumn 2001.
The average maximum temperature at Sydney Observatory Hill during Autumn was 22.7 °C, 0.5 °C above the historical average of 22.2 °C, with most of western Sydney recording below average temperatures. Temperatures were particularly warm during March, with several days above 30 °C during the first part of the month, while conditions were closer to average in April and May.
Minimum temperatures were also below average in the west but above average nearer the coast, with average minimums of 14.9 °C at Observatory Hill compared to the historical average of 14.6 °C. This was associated with lingering warm sea surface temperatures in the NSW region during the first part of the season as the La Niña event decayed in the Pacific, although temperatures were cooler than experienced in the autumns of 2009 and 2010.
Winds were predominantly southerly during Autumn, with 58% of 3pm winds between SE and SW, slightly above average for Autumn. A total of 13 strong wind days were reported during the season, particularly during May, which is slightly above average for Autumn.
Sunshine averaged 6.1 hours at Sydney Airport during Autumn, below the historical average of 6.4 hours and the lowest sunshine since 6.0 hours in Autumn 2001, with particularly low sunshine during March. Only one thunderstorm was reported at Sydney Airport during Autumn, below the historical average of 3-4 storms.
|Extremes in autumn 2011|
|Hottest day||36.6 °C at Badgerys Creek AWS on 1 Mar|
|Warmest days on average||23.5 °C at Liverpool (Michael Wenden Centre)|
|Coolest days on average||21.0 °C at Springwood (Valley Heights)|
|Coldest day||12.5 °C at Terrey Hills AWS on 25 May|
|Coldest night||-1.4 °C at Richmond RAAF on 16 May|
|Coolest nights on average||10.3 °C at Camden Airport AWS|
|Warmest nights on average||14.9 °C at Sydney (Observatory Hill)|
|Warmest night||23.0 °C at Sydney Airport AMO on 10 Mar|
|Warmest on average overall||18.8 °C at Sydney (Observatory Hill)|
|Coolest on average overall||16.5 °C at Springwood (Valley Heights)|
|Wettest overall||633.0 mm at Avalon (Wollstonecraft Ave)|
|Wettest day||178.6 mm at St Ives (Richmond Avenue) on 20 Mar|
|Highest wind gust||94 km/h at Fort Denison on 30 May|
|Summary statistics for autumn 2011|
|Badgerys Creek AWS||23.4||36.6||1 Mar||10.9||-0.1||16 May||162.2|
|Bankstown Airport AWS||22.9||-0.5||34.0||1 Mar||12.6||-0.2||2.5||11 May||283.4||252.0||average||112%|
|Camden Airport AWS||23.1||-0.6||34.8||1 Mar||10.3||-0.7||-1.3||16 May||197.8||209.0||average||95%|
|Campbelltown (Mount Annan)||23.3||35.1||1 Mar||10.6||-0.2||11 May||183.4|
|Canterbury Racecourse AWS||22.7||33.9||1 Mar||12.4||2.0||11 May|
|Holsworthy Control Range||22.9||34.9||1 Mar||11.7||-0.1||11 May|
|Horsley Park Equestrian Centre AWS||22.8||33.6||13 Mar||12.1||1.6||16 May||130.8|
|Liverpool (Michael Wenden Centre)||23.5||35.2||1 Mar||1.2||11 May||236.9|
|Parramatta North (Masons Drive)||22.8||-0.8||33.5||1 Mar||12.4||-0.5||3.8||15 May||401.6||268.7||high||149%|
|Penrith Lakes AWS||23.3||33.4||13 Mar||12.6||2.6||12 May||197.0|
|Prospect Reservoir||22.8||-0.6||33.5||13 Mar||12.5||-0.5||2.7||15 May||242.2||241.7||average||100%|
|Richmond RAAF||22.9||32.9||13 Mar||11.1||-1.4||16 May||212.6|
|Riverview Observatory||22.4||-0.1||34.7||1 Mar||13.1||+0.1||5.1||11 May||444.7||340.2||high||131%|
|Springwood (Valley Heights)||21.0||31.0||22 Mar||12.1||3.5||16 May||263.6||288.3||average||91%|
|Sydney (Observatory Hill)||22.7||+0.5||33.6||1 Mar||14.9||+0.3||7.3||15 May||533.4||376.8||high||142%|
|Sydney Airport AMO||22.6||-0.1||34.4||1 Mar||14.8||+0.6||6.6||15 May||486.2||322.4||high||151%|
|Sydney Olympic Park (Sydney Olympic Pk A||23.0||34.3||1 Mar||14.1||5.7||11 May|
|Terrey Hills AWS||21.2||31.3||1 Mar||13.1||4.7||12 May||477.2|
A Seasonal Climate Summary is prepared to list the main features of the weather in Sydney - Greater Sydney 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 1 June 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 20 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
(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.