Monday, 1 June 2009 - Seasonal Climate Summary for Sydney - Greater Sydney - Product code IDCKGC15L0

Mild, wet autumn in Sydney

Summary

  • Above average rainfall over most of Sydney metropolitan area
  • Mild days - close to average daytime temperatures
  • Mild nights - above average minimum temperatures, 8th warmest on record
  • Slightly above average sunshine hours

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 majority of the Sydney metropolitan area recorded above average rainfall during autumn. However, Observatory Hill recorded slightly below average rainfall with a total of 339.0 mm for the season. The historic seasonal average1 is 377 mm. April was the wettest month with nearly half of Sydney's total autumn rainfall. There were 38 rain days during the season, very close to the historic average of 37 rain days. The highest rainfall totals for autumn were on Sydney's North Shore with 479.9 mm recorded at Berowra. The driest region was the far SW suburbs where the lowest total for the season was 188.0 mm at Camden Valley. The wettest single day was 116.8 mm at North Turramurra followed by 112.4 mm at Duffys Forest both on 9 March.

The majority of Sydney's autumn rainfall was associated three significant weather events; on the 1st April due to a coastal low pressure trough and moist easterly winds; on the 13th and 14th April associated with thunderstorms and strong convective activity, and finally, on 19−23 May associated with an east coast low and moist easterly winds.

Sydney's Warragamba Dam catchment area recorded variable autumn rainfall totals ranging from around 200−300 mm in the lower catchment to as little as 100 mm in the upper catchment near Goulburn. Storage levels have risen slightly over the autumn period and currently stand at around 61%. 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 autumn with above average temperatures over most of the metropolitan area. The average maximum (daytime) temperature at Observatory Hill during autumn was 23.0°C, which is 0.8°C above the historic average1 of 22.2°C. It ranks as Sydney's 27th warmest autumn out of 151 years of record. Maximum temperatures were generally consistant across metropolitan Sydney with slightly cooler temperatures in elevated suburbs.

The highest temperature at Sydney Observatory Hill during autumn was 29.3°C on 15 April while the highest over the Greater Sydney area was 34.2°C at Penrith Lakes AWS and Richmond on 25 March.

Sydney's autumn nights were mild with mostly above average minimums throughout the metropolitan area. The average minimum at Observatory Hill of 15.7°C was 1.1°C above the historic autumn average1 of 14.6°C. This ranks as 8th warmest over the 151 year record. The above average temperatures were partly due to the lack of any significant cold fronts reaching Sydney during autumn.

The lowest temperature at Sydney Observatory Hill during autumn was 9.6°C on 12 May while the lowest over the Greater Sydney area was 2.4°C at Camden Airport AWS on 12 and 17 May.

Wind

The prevailing coastal wind direction during autumn afternoons was between east and south for 63% of the time. The strongest wind gust was 82 km/h at Wattamolla on 31 March followed by 80 km/h at Badgerys Creek AWS on 25 March.

Other phenomena

There were 7thunderstorms reported in Sydney during autumn which is above the historic average of 5 for the season. The most severe was on 2 May with very heavy rain and local flash flooding in the Randwick-Coogee area as well as parts of the northern beaches. Randwick recorded 77 mm in approximately 2 hours during the storm, the wettest day in May since 1974. However, this storm was very isolated and all areas west of the CBD were unaffected.

The amount of sunshine in Sydney during autumn was slightly above the historical average. The average was 6.9 hours per day compared to the historic autumn average of 6.6 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 in the Sydney area

Hottest day
Highest temperature
34.2°C at Penrith Lakes AWS on 25 March
34.2°C at Richmond RAAF on 25 March
Warmest days on average
Highest mean daily maximum temperature
23.9°C at Campbelltown and at Liverpool
Coolest days on average
Lowest mean daily maximum temperature
21.7°C at Terrey Hills AWS
Coldest day
Lowest daily maximum temperature
14.5°C at Terrey Hills AWS on 30 May
Coldest night
Lowest temperature
2.4°C at Camden Airport AWS on 12 May
2.4°C at Camden Airport AWS on 17 May
Coolest nights on average
Lowest mean daily minimum temperature
11.5°C at Camden Airport AWS and Campbelltown
Warmest nights on average
Highest mean daily minimum temperature
15.7°C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature
22.9°C at Sydney Airport on 4 March
Wettest overall
Highest total rainfall
479.9 mm at Berowra
458.1 mm at St Ives
458.0 mm at Randwick
Driest overall
Lowest total rainfall
188.0 mm at Camden Valley
Wettest day
Highest daily rainfall
116.8 mm at North Turramurra on 9 March
Highest wind gust
82 km/h at Wattamolla on 31 March
80 km/h at Badgerys Creek AWS on 25 March

Records

Nil recorded


Summaries for the Sydney area

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

Summary statistics for autumn 2009
Maximum temperatures
for autumn
(°C)
Minimum temperatures
for autumn
(°C)
Rainfall
for autumn
(millimetres)
Mean for
autumn
2009
Diff
from
average
Highest for
autumn
2009
Mean for
autumn
2009
Diff
from
average
Lowest for
autumn
2009
Total for
autumn
2009
Average
for
autumn
Rank of
autumn
2009
Fraction of
autumn
average
Sydney (Observatory Hill) 23.0 +0.8 29.3 15 Apr 15.7 +1.1 9.6 12 May 339.0 376.6 average 90%
Bankstown Airport AWS 23.4 0.0 32.3 26 Mar 13.2 +0.4 5.0 14 May 354.4 252.5 high 140%
Camden Airport AWS 23.7 0.0 33.1 26 Mar 11.5 +0.6 2.4 12 May 250.2 213.5 high 117%
Parramatta 23.5 −0.1 33.2 25 Mar 13.4 +0.5 6.2 13 May 308.9 267.4 high 116%
Penrith Lakes AWS 23.8 −0.6 34.2 25 Mar 13.4 +0.4 4.7 14 May 219.2 149.2 high 147%
Prospect Reservoir 23.7 +0.3 33.5 25 Mar 13.1 +0.1 5.8 12 May 257.3 242.3 average 106%
Richmond RAAF 23.4 −0.4 34.2 25 Mar 12.2 +0.7 2.7 17 May 253.8 169.8 average 149%
Sydney Airport 23.1 +0.4 30.9 26 Mar 15.6 +1.4 9.1 12 May 353.2 320.9 average 110%
Terrey Hills AWS 21.7   29.5 26 Mar 13.9   7.7 12 May 451.8

Notes

This statement has been prepared based on information available at 10 am on Monday 1 June 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.