Sydney in autumn 2011: Wettest Autumn since 2003

  • Wettest Autumn since 2003
  • Wettest Autumn day since 1998
  • Above average temperatures at Sydney Observatory Hill, below average in the west

Rainfall

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.

Temperature

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.

Wind

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.

Other phenomena

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.

Further information

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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 gust94 km/h at Fort Denison on 30 May

Summary statistics for autumn 2011
Maximum temperatures
for autumn
(°C)
Minimum temperatures
for autumn
(°C)
Rainfall
for autumn
(millimetres)
Mean for
autumn
2011
Diff
from
average
Highest for
autumn
2011
Mean for
autumn
2011
Diff
from
average
Lowest for
autumn
2011
Total for
autumn
2011
Average
for
autumn
Rank of
autumn
2011
Fraction of
autumn
average
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

Notes

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 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