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.

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

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


Records

Nil recorded


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

Notes

This statement has been prepared based on information available at 9 am on Monday 2 March 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 10 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

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