Monday, 2 March 2009 - Seasonal Climate Summary for Sydney - Greater Sydney - Product code IDCKGC25L0

Sydney has wet end to a warm summer

Summary

• Below average rainfall overall but wet end to summer
• Warm days - above average daytime temperatures
• Mild nights - above average minimum temperatures along coast
• Slightly above average sunshine

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

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Rainfall

The total summer rainfall of 206.6 mm at Sydney (Observatory Hill) was below the historic summer average¹ of 297 mm but was not exceptionally low (falling in the 4th decile of the rainfall record). More than half of Sydney's total summer rainfall occurred during one week in mid February with generally dry conditions in December and January. There were 31 rain days, which is below the historic average of 36 rain days. The highest rainfall totals for summer were on Sydney's North Shore with 369.0 mm at St Ives. The driest regions were in parts of the western and southern suburbs, the lowest total for the season being 190.0 mm at Sydney Airport.

The majority of Sydney's summer rainfall was associated with an intense cut off low pressure system on 13 December and an east coast low from 13−17 February. Most other falls were from thunderstorms associated with instability in low pressure troughs, typical during the summer period.

Sydney's Warragamba Dam catchment area recorded variable summer rainfall totals ranging from around 160 mm in the upper catchment (Goulburn area) to over 230 mm in parts of the lower catchment, which is close to the historic summer average. Katoomba, on the catchment divide, recorded a total of 443 mm during summer. Storage levels have fallen slightly over the summer period and currently stand at around 60%. 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 warm summer with above average temperatures over most of the metropolitan area. The average maximum (daytime) temperature at Observatory Hill during summer was 26.4°C, which is 0.8°C above the historic average¹ of 25.6°C. This falls in the warmest 11% of all summers over the past 151 years of record. Although there were several hot days, temperatures in coastal suburbs were moderated by the influence of sea breezes. The western suburbs recorded summer temperatures several degrees warmer than the coast but still about 1°C above the historic average maximum.

Although heatwave conditions occurred in the western suburbs during parts of January and early February, the remainder of summer was mild to warm. A cool spell followed the heatwave with maximum temperatures only reaching 15.9°C at Springwood in the Lower Blue Mountains on 14 February. Penrith recorded 8 very hot days (above 40°C) during summer compared to the summer average of only 3 days. This is the highest number of over 40°C days ever recorded during summer at both the Penrith site (with short record, since 1995) and Richmond sites (records since 1940).

The highest temperature at Sydney Observatory Hill during summer was 40.9°C on 24 January while the highest over the Greater Sydney area was 43.3°C at Penrith Lakes AWS on 15 January.

Sydney's summer nights were generally mild with above average minimums along the coast and slightly below average minimums in the far western suburbs. The average minimum at Observatory Hill of 19.2°C was 0.9°C above the historic summer average¹ of 18.3°C. This ranks as equal 18th warmest over the 151 year record. It is also the 13th consecutive summer with above average minimum temperatures at Observatory Hill. The mild overnight conditions along the coast was partly due to the moderating influence of the ocean and prevailing NE winds during summer.

The lowest temperature at Sydney Observatory Hill during summer was 14.3°C on 21 December while the lowest over the Greater Sydney area was 8.6°C at Camden Airport AWS on 21 December. During Sydney's heatwave in late January, several hot nights were recorded in the western suburbs. The minimum temperature of 25.9°C at Prospect Reservoir on 24 January was the 2nd warmest night recorded at that site in 43 years of record and the highest minimum temperature in the metropolitan area for this summer.

Wind

There were 30 windy days* in coastal Sydney during summer, well above the historic average of 19 windy days. The prevailing coastal wind direction during summer afternoons was E-NE for 55% of the time with another 37% from the S-SE. The highest wind gust recorded in the Sydney region was 93 km/h at Wattamolla (Royal National Park) on the 18 February associated with a small low pressure system off the NSW coast.

Other phenomena

There were 6 days on which thunderstorms were reported at the Sydney Observatory Hill site during summer which is below the historic average of 10 for the season. The most severe was on 21 February with Avalon Beach in Sydney's north recording 77 mm in about 2 hours. The storm caused flash flooding at Parramatta and Berowra with trees blown over and golf ball size hail at Cowan.

Although February was a cloudy, wet month, December and January had generally clear skies. Sunshine during summer averaged 7.7 hours per day, slightly above the historic summer average of 7.5 hours per day.

* Strong wind day defined as a day when average wind speed of 40 km/hr or more is recorded over a 10 minute period at least once in 24 hours.

Further information

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

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Extremes

Hottest day Highest temperature	43.3°C at Penrith Lakes AWS on 15 Jan 2009
Warmest days on average Highest mean daily maximum temperature	30.7°C at Penrith Lakes AWS
Coolest days on average Lowest mean daily maximum temperature	26.4°C at Sydney (Observatory Hill)
Coldest day Lowest daily maximum temperature	15.9°C at Springwood on 14 Feb 2009
Coldest night Lowest temperature	8.6°C at Camden Airport AWS on 21 Dec 2008
Coolest nights on average Lowest mean daily minimum temperature	16.0°C at Badgerys Creek AWS and at Camden Airport AWS
Warmest nights on average Highest mean daily minimum temperature	19.2°C at Sydney (Observatory Hill)
Warmest night Highest daily minimum temperature	25.9°C at Prospect Reservoir and Sydney Olympic Park on 24 Jan 2009
Wettest overall Highest total rainfall	369.0 mm at St Ives 350.4 mm at Berowra
Driest overall Lowest total rainfall	190.0 mm at Sydney Airport
Wettest day Highest daily rainfall	77.0 mm at Avalon Beach (24 hrs to 9am) on 22 Feb 2009 71.0 mm at Avalon (Wollstonecraft Ave) on 22 Feb 2009 70.4 mm at Camden Airport AWS on 13 Dec 2008
Highest wind gust	93 km/h at Wattamolla (Royal National Park) on 18 Feb 2009 81 km/h at Sydney Airport on 15 Jan 2009

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Records

Nil recorded

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Summaries

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

Summary statistics for Summer 2008−09
	Maximum temperatures for Summer 2008−09 (°C)				Minimum temperatures for Summer 2008−09 (°C)				Rainfall for Summer 2008−09 (millimetres)
	Mean for Summer 2008−09	Diff from average	Highest for Summer 2008−09		Mean for Summer 2008−09	Diff from average	Lowest for Summer 2008−09		Total for Summer 2008−09	Average for Summer 2008−09	Rank of Summer 2008−09	Fraction of Summer 2008−09 average
Sydney (Observatory Hill)	26.4	+0.8	40.9	24 Jan 2009	19.2	+0.9	14.3	21 Dec 2008	206.6	296.9	average	70%
Bankstown Airport AWS	28.6	+0.9	41.2	24 Jan 2009	17.6	0.0	10.7	21 Dec 2008	295.4	271.3	average	109%
Camden Airport AWS	30.0	+1.2	42.5	15 Jan 2009	16.0	−0.2	8.6	21 Dec 2008	233.4	244.2	average	96%
Parramatta North	29.0	+1.1	41.7	15 Jan 2009	17.4	+0.4	10.5	21 Dec 2008	240.4	302.2	average	80%
Richmond	29.4	+0.4	41.9	7 Feb 2009	16.4	−0.5	8.4	21 Dec 2008	237.6	270.6	average	88%
Prospect Reservoir	29.5	+1.6	41.9	7 Feb 2009	17.1	−0.1	10.7	21 Dec 2008	234.3	262.2	average	89%
Springwood	28.4		40.6	15 Jan 2009	16.4		10.0	21 Dec 2008	320.0	362.7	average	88%
Terrey Hills AWS	26.5		39.2	24 Jan 2009	17.4		11.3	21 Dec 2008	258.8

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Notes

Further information

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

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