Tuesday, 1 September 2009 - Seasonal Climate Summary for Sydney Rainfall Districts - Product code IDCKGC1xx0

Third warmest winter on record for Sydney

  • Mild to warm winter days, especially during August. Third warmest winter on record.
  • Mild nights, 3rd highest average minimum temperature on record
  • Below average winter rainfall, ranks in the lowest 30% of all totals
  • Slightly above average sunshine hours

An archive of previous seasonal summaries for Sydney Rainfall Districts is also available, as are summaries for other states and many other climate summaries and diagnostics.

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Rainfall

Sydney metropolitan area recorded below average rainfall during winter. Observatory Hill recorded a total of 188.8 mm for the season compared to historic average1 of 310 mm. Nearly 70% of Sydney's winter rain fell during a 3 week period in June, while July and August recorded well below average rainfall. There were only 26 rain days during the season, well below the historic winter average of 34 rain days. The highest rainfall totals for winter were in Sydney's coastal suburbs, the highest being 215.6 mm at Mona Vale. The driest region was the far west where the lowest total for the season was only 38.0 mm at Willmot. The wettest single day was 34.0 mm at Randwick Racecourse on 22 June.

The majority of Sydney's winter rainfall fell during June when moist onshore flows caused heavy showers in coastal suburbs. From about mid July dry prevailing westerly winds produced little significant rainfall.

Sydney's Warragamba Dam catchment area recorded below average winter rainfall. Most falls were between 60 and 100 mm over the catchment area. Storage levels have fallen over winter from 61% on 1 June to currently 59% of total capacity. Recent rainfall and current levels in Sydney's water catchments can be found on the Sydney Catchment Authority web site http://www.sca.nsw.gov.au/dams/rainfall.html

Temperatures

Sydney experienced a mild winter with above average temperatures over the whole of the metropolitan area. The average maximum (daytime) temperature at Observatory Hill during winter was 19.0°C, which is 2.0°C above the historic average1 of 17.0°C. It ranks as Sydney's equal 3rd warmest winter out of 151 years of record. Sydney's warmest winter was in 2005 (average 19.4°C) followed by 2004 (average 19.2°C). Maximum temperatures were generally consistent across metropolitan Sydney with slightly cooler temperatures in elevated suburbs. Sydney Airport recorded its warmest average maximum temperature on record for winter (19.3°C).

The above average winter temperatures were partly due to the lack of any significant cold fronts reaching Sydney and warm W-NW winds, especially during August. The highest temperature at Sydney Observatory Hill during winter was 25.7°C on 29 August while the highest over the Greater Sydney area was 27.3°C at Penrith Lakes AWS on 21 August.

Sydney's winter nights were mild with above average minimums throughout the metropolitan area. The average minimum at Observatory Hill of 10.0°C was 1.2°C above the historic winter average1 of 8.8°C. This ranks as equal 3rd warmest over the 151 year record. The warmest winter nights were in 1988 (average minimum 10.3°C) and in 1950 (average minimum 10.2°C).

The lowest temperature at Sydney Observatory Hill during winter was 5.9°C on 9 August while the lowest over the Greater Sydney area was −2.8°C at Camden Airport AWS also on 9 August.

Some sites had their highest winter mean daily maximum temperature on record.

Some sites had their warmest winter night (highest daily minimum temperature) on record.

Wind

Prevailing winds over coastal Sydney were SW-NW during winter for around 67% of the time, which is above the normal winter frequency (59%) from this direction. The strongest wind gust was 87 km/h at Holsworthy and at Sydney Airport on 25 August when a deep low pressure system brought strong to gale force westerly winds to southern NSW.

Other phenomena

Only one thunderstorm was recorded in Sydney during winter (11 August) compared to the normal 4 storms. Sunshine hours were slightly above the historic average during winter, averaging 7.0 hours per day. However, this was a combination of cloudy conditions in June (average 5.1 hours per day) and plentiful sunshine in August (average 8.6 hours per day).

Further information

Mike De Salis
Climate Officer
NSW Climate Services Centre
NSW Regional Office
Bureau of Meteorology
Phone (02) 9296 1555
Email climate.nsw@bom.gov.au

Extremes for the Sydney area

Hottest day
Highest temperature		 27.3°C at Penrith Lakes AWS on 21 Aug
Warmest days on average
Highest mean daily maximum temperature		 19.5°C at Sydney Olympic Park
Coolest days on average
Lowest mean daily maximum temperature		 17.5°C at Terrey Hills AWS
Coldest day
Lowest daily maximum temperature		 11.0°C at Bankstown Airport AWS on 14 Jun
Coldest night
Lowest temperature		 −2.8°C at Camden Airport AWS on the 9 Aug
Coolest nights on average
Lowest mean daily minimum temperature		 4.0°C at Camden Airport AWS
Warmest nights on average
Highest mean daily minimum temperature		 10.0°C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature		 19.2°C at Riverview Observatory on 24 Aug
Wettest overall
Highest total rainfall		 215.6 mm at Mona Vale
215.1 mm at Randwick Racecourse
Driest overall
Lowest total rainfall		 38.0 mm at Willmot
Wettest day
Highest daily rainfall		 34.0 mm at Randwick Racecourse on 22 Jun
33.8 mm at Mount Kuring-Gai on 22 Jun
Highest wind gust
 87 km/h at Holsworthy and Sydney Airport on 25 Aug

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Records

Record highest winter mean daily maximum temperature
Mean daily maximum
temperature
for winter 2009 (°C) 		Previous highest
for winter		 Years of
record		 Average for
winter
Sydney Airport 19.3 19.2 in 2005 71 17.6
Riverview Observatory 19.0 = 19.0 in 2005 23 18.0


Record highest winter daily minimum temperature
Highest daily minimum
temperature
in winter 2009 (°C) 		Previous highest
for winter		 Years of
record		 Average for
winter
Riverview Observatory 19.2 on 24 Aug 18.4 on 27 Aug 1995 24 7.7


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Summaries for the Sydney area

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

Summary statistics for winter 2009
Maximum temperatures
for winter
(°C)		 Minimum temperatures
for winter
(°C)		 Rainfall
for winter
(millimetres)
Mean for
winter
2009		 Diff
from
average		 Highest for
winter
2009		 Mean for
winter
2009		 Diff
from
average		 Lowest for
winter
2009		 Total for
winter
2009		 Average
for
winter		 Rank of
winter
2009		 Fraction of
winter
average
Sydney (Observatory Hill) 19.0 +2.0 25.7 29 Aug 10.0 +1.2 5.9 9 Aug 188.8 310.0 low 61%
Sydney Airport 19.3 +1.7 27.0 29 Aug 9.6 +1.7 5.1 9 Aug 142.6 267.1 low 53%
Bankstown Airport AWS 18.8 +0.9 26.9 29 Aug 6.1 +0.1 1.3 9 Aug 102.0 164.9 average 62%
Liverpool 19.3   27.2 29 Aug 5.0   −1.2 9 Aug 81.4
Parramatta North 19.2 +1.1 26.4 29 Aug 7.6 +0.7 2.4 9 Aug 96.4 186.3 average 52%
Penrith Lakes AWS 19.3   27.3 21 Aug 6.2   1.5 6 Jul 52.2
Prospect Reservoir 18.6 +1.0 26.8 29 Aug 6.9 +0.2 1.2 11 Jun 86.1 182.7 low 47%
Richmond RAAF 19.0 +1.1 26.8 29 Aug 4.8 +0.2 −2.4 11 Jun 53.0 138.1 low 38%
Camden Airport AWS 18.7 +0.7 27.1 29 Aug 4.0 +0.3 −2.8 9 Aug 58.6 140.6 low 42%
Terrey Hills AWS 17.5   24.6 23 Aug 8.8   3.1 6 Jul 97.2

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Notes

This statement has been prepared based on information available at 12 pm on Tuesday 1 September 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 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

Mike De Salis
Climate Officer
NSW Climate Services Centre
NSW Regional Office
Bureau of Meteorology
Phone (02) 9296 1555
Email climate.nsw@bom.gov.au