Sydney - Greater Sydney in summer 2011-12

Sydney in summer 2011-12: A cool, wet summer for Sydney

  • Above average rainfall, wettest in northern and western Sydney
  • Most rain days since summer 1998/9
  • Below average maximum temperatures, coolest since 1996/7

Rainfall

Sydney Observatory Hill recorded 328.2 mm of rain during summer, slightly above the historical average of 297.1 mm. Rainfall was heaviest during January, which was the wettest since 2001, but closer to average during December and February. The rain fell over 48 rain days, well above the average of 36 rain days and the most for Sydney since 49 days in summer 1998/9. However, Sydney Observatory Hill missed out on several major rain events during the season, with most of the city recording more than 400 mm, including large areas above 500 mm in northern Sydney. The highest total anywhere in Sydney was 692 mm in Berowra, while Berowra, Glenorie, Turramurra and Kings Langley all recorded their wettest summer since 1991/2.

Around the Greater Sydney area, several days had totals above 50 mm during the season, mostly associated with thunderstorm activity. Particularly heavy thunderstorms brought totals of up to 77 mm at Turramurra to 9am on the 12th, including 26 mm in 10 minutes at Mt Kuring-gai. Thunderstorms also brought totals as high as 84 mm to 9am on January 9th, while localised falls of up to 115.4 mm at Penrith Lakes on February 10th caused flash flooding in western Sydney. Further thunderstorms on the 19th and 20th of February caused totals of up to 85 mm at Mona Vale on the 21st, with further flash flooding in southern Sydney. The passage of low pressure troughs also brought additional rain to Sydney during the season, with particularly heavy falls during 15-16 January and 26 January.

At the end of summer, Sydney's water storages were at 87.4% of capacity, an increase of 15% from the end of summer 2010-11. For more information please see our Water Storages website.

Temperature

The average maximum temperature at Sydney Observatory Hill during summer was 25 °C, 0.6 °C below average and the coolest summer since 24.9 °C was recorded in 1996/7. Days were colder than average throughout the city, with both Parramatta North and Camden experiencing their coldest summer on record. Cool conditions were persistent throughout the season, consistent with above average cloud cover and prevailing La Niña conditions, but especially during December, which was the coolest since 1960 at Observatory Hill and the coldest on record at several Sydney stations. In particular, there were eight consecutive days below 23 °C at the start of December, the first such cold spell in summer since 19-26 December 1967.

The cool temperatures were associated with a lack of hot days, with only two days reaching 30 °C at Sydney Observatory Hill during the season, the fewest hot days since 2007/8 and the 6th time on record with less than 3 hot days. In western Sydney, Parramatta recorded just 9 days above 30 °C (average 26 days), its fewest on record, with 15 days above 30 °C at Richmond (average 36 days), the fewest since summer 1971/2. The lack of hot days was associated with generally above average cloudiness and a lack of hot northwesterly winds during the season.

The average minimum temperature at Sydney Observatory Hill was 18.5 °C during summer, slightly above the historical average of 18.3 °C but the coolest nights since 18.4 °C in summer 1999/2000, while most of western Sydney experienced below average minimums during the season. The mild nights were associated with increased cloud cover during summer, with above average nights during January when rainfall was highest.

The mean temperature at Sydney Observatory Hill during summer was consequently 21.8 °C, 0.2 °C below the historical average. This is the coolest summer since 21.7 °C was recorded in summer 1996/7, and the first summer with below average temperatures since 1998/9.

Some sites had their lowest summer mean temperature on record. Some sites had their lowest summer mean daily maximum temperature on record.

Wind

Winds during summer were predominantly easterly, with 64% of 3pm winds between NE and SE, while an additional 28% of winds were between SSE and SSW, with a slightly lower frequency of westerly winds than normal for summer. Only 3 strong wind days were reported at Sydney Airport, well below the historical average of 17 days and the fewest since 1988/9, with a maximum wind gust of just 76 km/hr during a thunderstorm on January 11.

Other phenomena

Sydney Airport recorded an average of 6.9 hours of bright sunshine during summer, below the historical average of 7.6 hours and the lowest sunshine since the summer of 2007/8. There were 43 cloudy days during the season, close to the average of 38 days; however, only 9 clear days were reported, the fewest since 7 clear days in summer 1954/5.

Eight thunderstorms were reported at Sydney Airport, close to the historical average of 9 storms. There were 19 storms reported anywhere in the Metropolitan region during summer, normal for Sydney, with four reports of hail.

Further information

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Extremes in summer 2011-12
Hottest day 37.3 °C at Penrith Lakes AWS on 4 Jan 2012
Warmest days on average 26.9 °C at Penrith Lakes AWS
Coolest days on average 23.4 °C at Terrey Hills AWS
Coldest day 16.5 °C at Springwood (Valley Heights) on 6 Dec 2011
16.5 °C at Springwood (Valley Heights) on 1 Feb 2012
16.5 °C at Springwood (Valley Heights) on 2 Feb 2012
Coldest night 7.4 °C at Camden Airport AWS on 7 Dec 2011
Coolest nights on average 15.2 °C at Campbelltown (Mount Annan)
Warmest nights on average 18.6 °C at Sydney Airport AMO
Warmest night 25.3 °C at Sydney (Observatory Hill) on 31 Jan 2012
Warmest on average overall 21.9 °C at Sydney Airport AMO
Coolest on average overall 19.7 °C at Springwood (Valley Heights)
Wettest overall692.2 mm at Berowra (Goodwyn Road)
Wettest day 115.4 mm at Penrith Lakes AWS on 10 Feb 2012
Highest wind gust 83 km/h at Kurnell AWS on 11 Jan 2012


Record lowest summer mean daily maximum temperature
Mean daily maximum
temperature
for summer 2011-12 (°C)
Previous coolest
for summer
Years of
record
Average for
summer
Parramatta North (Masons Drive) 25.2 25.8 in 1995 42 27.9
Camden Airport AWS 26.1 26.6 in 1983 35 28.9



Record lowest summer mean temperature
Mean daily
temperature
for summer 2011-12 (°C)
Previous coolest
for summer
Years of
record
Average for
summer
Parramatta North (Masons Drive) 20.8 20.9 in 1995 42 22.5
Camden Airport AWS 20.7 21.1 in 1983 35 22.6



Summary statistics for summer 2011-12
Maximum temperatures
for summer
(°C)
Minimum temperatures
for summer
(°C)
Rainfall
for summer
(millimetres)
Mean for
summer
2011-12
Diff
from
average
Highest for
summer
2011-12
Mean for
summer
2011-12
Diff
from
average
Lowest for
summer
2011-12
Total for
summer
2011-12
Average
for
summer
Rank of
summer
2011-12
Fraction of
summer
average
Badgerys Creek AWS 26.0   35.0 4 Jan 2012 15.7   8.7 5 Dec 2011 412.6
Bankstown Airport AWS 26.0 -1.8 36.2 4 Jan 2012 16.8 -0.8 9.7 7 Dec 2011 359.4 266.5 high 135%
Camden Airport AWS 26.1 -2.8 36.4 4 Jan 2012 15.4 -0.9 7.4 7 Dec 2011 292.4 240.4 high 122%
Campbelltown (Mount Annan) 25.9   34.8 4 Jan 2012 15.2   7.6 5 Dec 2011 268.4
Canterbury Racecourse AWS 24.8   35.6 4 Jan 2012 16.8   8.6 7 Dec 2011 392.6
Holsworthy Control Range 25.5   35.4 4 Jan 2012 15.7   7.9 7 Dec 2011 331.8
Horsley Park Equestrian Centre AWS 25.6   35.2 4 Jan 2012 16.1   9.9 5 Dec 2011 429.6
Parramatta North (Masons Drive) 25.2 -2.7 36.1 4 Jan 2012 16.3 -0.8 9.5 3 Dec 2011 466.6 304.3 high 153%
Penrith Lakes AWS 26.9   37.3 4 Jan 2012 16.8   10.2 3 Dec 2011 492.4
Prospect Reservoir 25.8 -2.1 34.9 4 Jan 2012 16.6 -0.6 10.5 3 Dec 2011 435.8 265.0 high 164%
Richmond RAAF 26.1   36.2 4 Jan 2012 16.4   8.6 12 Jan 2012 379.2
Riverview Observatory 24.7 -1.5 33.2 4 Jan 2012 17.0 -0.2 10.0 7 Dec 2011 504.1 303.3 v high 166%
Springwood (Valley Heights) 24.2   36.3 4 Jan 2012 15.3   8.3 5 Dec 2011 492.2 367.8 high 134%
Sydney (Observatory Hill) 25.0 -0.6 33.4 28 Feb 2012 18.5 +0.2 11.8 5 Dec 2011 328.2 297.3 average 110%
Sydney Airport AMO 25.2 -1.0 34.6 30 Jan 2012 18.6 +0.2 12.0 5 Dec 2011 357.6 281.2 high 127%
Terrey Hills AWS 23.4   31.8 4 Jan 2012 16.6   9.5 5 Dec 2011 543.0

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 11 am on Thursday 1 March 2012. 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