Thursday, 1 October 2009 - Monthly Climate Summary for Sydney - Greater Sydney - Product code IDCKGC25L0

Dry, with record high temperatures in Sydney during September

  • Equal highest average mean temperature (average of maximum and minimum)
  • Equal 2nd highest average maximum temperature on record
  • Highest average minimum temperature on record
  • Very dry; below average rainfall and relative humidity
  • High incidence of strong westerly winds
  • Major duststorm on 23rd, worst for 67 years
  • Sunny month with many clear days

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

Rainfall

After a dry August, very dry conditions continued throughout Sydney during September. Observatory Hill had a total rainfall of only 16.0 mm, which is well below the historical September average of 69.4 mm. This ranks as the 19th driest September out of 152 years of record at Observatory Hill. The rain fell on only 4 days, which is well below the average of 11 rain days. The entire metropolitan area recorded below average rainfall. Slightly higher totals occurred in the SW with lower totals along the coast and over the northern metropolitan. Monthly totals ranged from 34.6 mm at Campbelltown to only 4.2 mm at Richmond. A thunderstorm on the 22nd produced 16 mm at Sydney Olympic Park, the highest daily rainfall in the metropolitan area during September.

The lack of any significant rainfall was mainly due to the continuing prevailing and dry W-NW winds throughout the month with a low incidence of rain bearing systems. Except for a few weak afternoon sea breezes there was virtually a complete lack of onshore winds. At some sites the prevailing W-NW wind occurred up to 77% of the time, well above the normal frequency of 53% at 9am. These conditions also produced very low humidity levels throughout Sydney with a monthly average at 3pm of 44% at Observatory Hill, the 5th lowest for September over the past 55 years of humidity records. The historic average at this time is 51%.

Dry conditions also prevailed over the lower Warragamba Dam catchment. However, the upper catchment (near Goulburn) received falls of up to 60 mm for the month. The dry weather caused Sydney's storage level to fall by 1% during September and is currently around 58% of 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

Some sites had their lowest total September rainfall on record.

Some sites had their lowest total September rainfall for at least 20 years.

Temperatures

Sydney experienced its equal hottest September on record. The average mean temperature (average of maximum and minimum) was 18.3° which is 2.8°C above the historic mean average and the same as the year 2006. Daytime temperatures were well above average with many warm days and the occasional hot day. Observatory Hill recorded an average maximum temperature of 23.1°C, which is a significant 3.2°C above the historical September average. This is Sydney's equal 2nd highest average maximum temperature for September in the 151 year record with identical average maximums also recorded in 1928 and 2006. Sydney's warmest September was in 1980 (23.3°C)

Observatory Hill recorded 2 hot days (maximum temperature greater than 32°C) during the month. This has occurred only once before, in 2008 (records since 1859). Days over 32°C are rare in September; with a typical occurrence of once in every 10 years. However, the frequency of hot days in September has rapidly increased recently, with 32°C being exceeded 7 times in the last decade.

Plentiful sunshine, prevailing W-NW winds and the lack of any significant cool changes contributed towards the warm conditions. The above average temperatures in Sydney are consistent with warmer than average conditions experienced across eastern and northern Australia during September. An El Niño) event is currently maturing in the equatorial Pacific Ocean. These events are usually (but not always) associated with above average temperatures in eastern Australia. Very high temperatures experienced throughout August and September are likely due to the current influence of El Niño) combined with the background, long-term warming that has been observed across Australia since the start of last century.

Very mild nights were also experienced throughout the metropolitan area during the month with Sydney Observatory Hill recording its highest average minimum temperature on record for September. The average minimum of 13.5°C was 2.5°C above the historic average. The previous highest was 13.4°C in 1998 and 2006. There were 13 mild nights in Sydney (minimum 14°C or higher), equal to the highest number recorded in 1998. The normal frequency for September is 4 nights above 14°C.

The particularly high minimums around Sydney is partly due to persistent, warm W-NW winds and a slight warming effect at night (Foehn wind effect) as prevailing westerly winds descended over the Sydney basin.

There was significant variation in temperatures over the Sydney region during September, with extremes ranging from a high of 33.2°C at Liverpool and Sydney Airport on the 17th to a low of 2.0°C at Camden Airport AWS on the 10th and 11th and 2.0°C at Campbelltown on the 11th.

Some sites had their highest September mean daily maximum temperature for at least 20 years.

Some sites had their highest September mean daily minimum temperature on record.

Wind

There was a significantly higher than normal incidence of winds from the W-NW winds during September with frequencies around 77% at Sydney Airport during the mornings (normal frequency 53%). Over half the daily maximum gusts at the airport were also from this direction with the highest gust of 81 km/hr (from west) on the 23rd. The highest gust in the Metropolitan area was WNW at 85 km/hr at Richmond on the 7th.

Other phenomena

A major duststorm with strong winds hit Sydney during the morning of the 23rd producing a blood red sky and reducing visibility to 400 metres over much of the city. A thick layer of red dust coated all exposed surfaces with many flights delayed or cancelled at Sydney Airport. The dust, originating from South Australia and western NSW, was the worst duststorm in Sydney since 1942. A few days later, strong winds again caused raised dust on the 26th reducing visibility to 4 km at 6am.

Observatory Hill recorded 2 thunderstorms on the 7th and 22nd with a third storm passing over northern suburbs on the 20th. Small hail (1 cm) was reported with all 3 storms in various suburbs with hail up to 2 cm at Hornsby on the 22nd. Sunshine averaged 8.8 hours per day, the highest since 2002 and well above the historical average of 7.9 hours per day.

Further information

Mike De Salis
Climate Monitoring 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
33.2°C at Liverpool and Sydney Airport on the 17th
Warmest days on average
Highest mean daily maximum temperature
24.9°C at Penrith Lakes AWS
Coolest days on average
Lowest mean daily maximum temperature
21.8°C at Terrey Hills AWS
Coldest day
Lowest daily maximum temperature
15.4°C at Springwood on the 27th
Coldest night
Lowest temperature
2.0°C at Camden Airport AWS on the 10th and 11th
2.0°C at Campbelltown (Mount Annan) on the 11th
Coolest nights on average
Lowest mean daily minimum temperature
7.5°C at Camden Airport AWS
Warmest nights on average
Highest mean daily minimum temperature
13.5°C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature
19.0°C at Sydney (Observatory Hill) on the 18th
Wettest overall
Highest total rainfall
34.6 mm at Campbelltown (Mount Annan)
Driest overall
Lowest total rainfall
4.2 mm at Richmond RAAF
Wettest day
Highest daily rainfall
16.0 mm at Sydney Olympic Park on the 23rd
Highest wind gust
85 km/h at Richmond RAAF on the 7th

Records

Lowest total September rainfall for at least 20 years
Total rainfall
for September 2009 (mm)
Most recent lower
for September
Years since
lower
Average for
September
Rose Bay 7.8 1.0 in 1989 20 72.2



Highest September mean daily maximum temperature for at least 20 years
Mean daily maximum
temperature
for September 2009 (°C)
Most recent higher
for September
Years since
higher
Average for
September
Sydney Airport 23.5 24.0 in 1980 29 20.4



Record highest September mean daily minimum temperature
Mean daily minimum
temperature
for September 2009 (°C)
Previous highest
for September
Years of
record
Average for
September
Sydney (Observatory Hill) 13.5 13.4 in 2006 150 11.0
Parramatta 10.7 = 10.7 in 1986 41 9.3



Summaries for the Sydney area

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

Summary statistics for September 2009
Maximum temperatures
for September
(°C)
Minimum temperatures
for September
(°C)
Rainfall
for September
(millimetres)
Mean for
September
2009
Diff
from
average
Highest for
September
2009
Mean for
September
2009
Diff
from
average
Lowest for
September
2009
Total for
September
2009
Average
for
September
Rank of
September
2009
Fraction of
September
average
Sydney (Observatory Hill) 23.1 +3.2 32.2 13th 13.5 +2.5 9.5 11th 16.0 69.1 low 23%
Bankstown Airport AWS 23.5 +2.1 32.5 17th 9.5 +0.9 4.2 10th 16.4 44.6 low 37%
Camden Airport AWS 23.6 +1.8 32.8 17th 7.5 +0.8 2.0 10th 34.4 39.5 average 87%
Parramatta 23.8 +2.3 32.0 17th 10.7 +1.4 6.1 11th 23.6 53.7 low 44%
Penrith Lakes AWS 24.9   33.1 17th 9.3   4.2 11th 13.8
Prospect Reservoir 24.0 +2.8 31.7 13th 11.5 +2.2 5.2 11th 16.1 47.2 low 34%
Richmond RAAF 23.9 +2.4 32.1 17th 8.6 +3.0 2.1 11th 4.2 39.5 very low 10%
Springwood 22.7   31.2 17th 10.4   6.1 11th 17.8 55.8 low 32%
Sydney Airport 23.5 +3.0 33.2 17th 13.0 +2.7 8.7 11th 21.6 61.2 low 35%
Terrey Hills AWS 21.8   30.3 17th 11.9   7.8 1st 9.2

Daily rainfall for the Sydney region

Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with »» are part of a longer accumulation, which is marked like this on the final day. Values over 100 mm have been rounded to the nearest whole millimetre. Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.

Hunter (61)123456789101112131415161718192021222324252627282930
Wisemans Ferry - - - 2.8 1.0 0.2 - - 0.2 - - - - - - - - - - - 0.6 0.2 0.8 - - - - - - -
Central Tablelands (South) (63)123456789101112131415161718192021222324252627282930
Sackville Ferry (Hawkesbury River) - - - 5.4 5.0 - - - - - - - - - - - - 0.2 - - 0.2 0.8 0.4 - - - - - - -
Springwood - - - 5.0 - - - 0.6 - - - - - - 0.4 - 0.2 - - - - 0.4 10.8 - - - 0.4 - - -
Valley Heights (Sun Valley Rd) - - - 4.8 - - - 0.4
-
-

0.6 -
-
- - 0.6 10.8
- - 0.6
-
Metropolitan (East) (66)123456789101112131415161718192021222324252627282930
Auburn (Rosnay Golf Club) - - - 3.0 - - - 1.0 - - - - - - - - - - - - - - 12.0 - - - - - - -
Audley (Royal National Park) - - - 5.0 - - - 5.0 - - - - - - - - - - - - 3.0 1.0 11.0 - - - - - - -
Avalon (Wollstonecraft Ave) - - - 3.0 - - - 1.0 - - - - - - - - - - - - - 1.0 - - - - - - - -
Bankstown Airport AWS - - - 3.8 0.2 - - 0.2 0.2 - - - - - - - - - - - 0.6 0.2 11.2 - - - - - - -
Belrose (Evelyn Place)


3.6















2.2 0.4 1.2






Campbelltown (Ingleburn) - - - 7.0 - - - 3.0 - - - - - - - - - - - - 1.0 - 13.0 - - - - - - -
Canterbury Racecourse AWS - - - 3.0 0.2 - - 3.8 0.2 - - - - - - - - - - - - - 11.8 0.2 - - - - - -
Castle Cove (Rosebridge Ave)


2.2


1.1












1.0







Chatswood Bowling Club - - - 4.0 - - - 2.0 - - - - - - - - - - - - - - 2.0 - - - - - - -
Concord Golf Club


5.0



5.6




















Cronulla South Bowling Club


6.4















1.6 0.6 7.0






Guildford (Woodville Golf Club) - - - 3.0 - - - 1.0 - - - - - - - - - - - - - - 14.0 - - - - - - -
Holsworthy Control Range - - - 5.8 0.2 - - 2.6 0.2 - - - - - - - 0.2 - - - 0.2 - 12.0 - - - - - - -
Lidcombe (Carnarvon Golf Club) - - - 4.0 - - - 1.0 - - - - - - - - - - - - - - 9.0 - - - - - - -
Liverpool-Scrivener St (Georges River) - - - 4.0 - - - 1.0 - - - - - - - - - - - - 2.0 - 6.0 - - - - - - -
Lucas Heights (ANSTO)


5.8


8.8











0.6 1.4 11.0






Manley / Warringah (Allambie) - - - 2.5 - - - 0.5 - - - - - - - - - - - - 1.0 - 1.5 - - - - - -
Manley / Warringah (Belrose)
- - 2.5 -
- - -
- -
- - - - -

2.0
1.0 - - - -


Marrickville Golf Club - - - 3.0 - - - 2.0 - - - - - - - - - - - - - - 12.0 - - - - - - -
Milperra Bridge (Georges River) - - - 2.0 - - - - - - - - - - - - - - - - 3.0 - 9.0 - - - - - - -
Mona Vale Golf Club - - - 3.6 - - - 0.2 - - - - - - - - - - - - 6.8 0.2 0.4 - - - - - - -
Parramatta North (Masons Drive) - - - 5.6 - - - 5.0 - - - - - - - - - - - - 2.6 0.4 10.0 - - - - - - -
Randwick Bowling Club


5.6


6.2













4.0






Riverview Observatory - - 0.1 4.4 - - - 3.8 - - - - - - - - 0.2 - - - - - 4.6 - - - - - - -
Rose Bay (Royal Sydney Golf Club)


4.6


3.2





















Sans Souci (Public School) - - - 5.0 - - - - - - - - - - - - - - - - - - 6.0 - - - - - - -
St Ives (Richmond Avenue)


3.6


-











9.6 0.4







Strathfield Golf Club - - - 3.0 - - - 2.0 - - - - - - - - - - - - - - 12.0 - - - - - - -
Sydney (Observatory Hill) - - - 6.0 - - - 5.4 0.2 - - - - - - - - - - - - - 4.4 - - - - - - -
Sydney Airport - - - 4.4 - - - 6.2 - - - - - - - - - - - - 1.0 - 10.0 - - - - - - -
Sydney Olympic Park - - - 5.2 0.8 - - 3.6 - - - - - - - - - - - - - - 16.0 - - - - - - -
Terrey Hills AWS - - - 3.2 - - - - 0.2 - - - - - - - 0.2 - - - 5.2 0.2 0.2 - - - - - - -
Turramurra (Kissing Point Road)


4.2


0.6











8.6 0.6 1.6





-
West Pymble (Wyuna Road)


4.0


1.0











6.0








Metropolitan (West) (67)123456789101112131415161718192021222324252627282930
Abbotsbury (Fairfield City Farm) - - - 4.0 - - - - - - - - - - - - - - - - - - 6.0 - - - - - - -
Badgerys Creek AWS - - - 7.6 - - - 5.0 0.2 - - - - - - - - 0.2 - - 1.0 0.2 12.6 0.2 - - - - - -
Baulkham Hills (Swimming Pool ) - - - 5.0 - - - 0.5 - - - - - - - - - - - - 7.5 0.5 7.0 - - - - - - -
Baulkham Hills Eucalyptus Ct - - - 5.5 - - - 1.5 - - - - - - - - - - - - 7.0 0.5 10.5 - - - - - - -
Berowra (Goodwyn Road)


3.8
















2.4







Blacktown (Dog Pound) - - - 3.5 - - - - - 0.5 - - - - - - - - - - 0.5 - 9.0 - - - - - - -
Box Hill (Hynds Road) - - - 3.0 1.0 - - - - - - - - - -
- - - - - - 2.0 - - - - - - -
Castle Hill (Kathleen Ave)


5.4


1.4











11.0 0.5 6.4






Glenorie (Old Northern Rd)


5.4



1.0










3.0








Greystanes (Cumberland Golf Club) - - - 4.0 - - - - 0.5 - - - - - - - - - - - - - 11.0 - - - - - - -
Horsley Park Equestrian Centre AWS - - - 4.0 0.2 - - - 0.6 0.2 - - - - - - - 0.2 - - 0.2 - 8.4 - - - - - - -
Kelso Ck (Panania) - - - 5.0 - - - 1.0 - - - - - - - - 1.0 - - - - - 9.5 - - - - - - -
Kings Langley (NSW Soccer Federation) 0.5 - - 5.0 - - - 1.5 - - - - - - - - - - - - 10.0 1.0 8.0 - - - - - - -
Kings Langley (Solander Rd) - - - 5.4 - - - 3.8 - - - - - - - - 0.2 - - - 7.2 0.8 10.2 - - - - - - -
Liverpool (Michael Wenden Centre) - - - 6.2 - - - 3.6 - - - - - - - - 0.2 - - - 1.0 - 9.6 - - - - - - -
Lower Portland (Hawkesbury River) - - - 4.8 1.4 - - 1.4 - - - - - - - - - - - - 4.8 1.0 1.0 - - - - - - -
Maroota (Tobruk) - - 0.2 6.0 1.0 - - 0.2 - - - - - - - - 0.4 - - - 2.4 1.4 0.6 - - - - - - -
Merrylands (Welsford Street)


5.4

















13.8






Merrylands West (Finlayson Creek) - - - 3.5 - - - 0.5 0.5 - - - - - - - - - - - - - 10.5 - - - - - - -
North Parramatta (Burnside Homes) - - - 4.5 0.5 - - 4.0 - - - - - - - - - - - - 2.0 - 9.0 - - - - - - -
North Rocks (Muirfield Golf Club) - - - 7.5 - - - 1.5 - - - - - - - - - - - - 7.0 0.5 12.5 - - - - - - -
Northmead Bowling Club - - - 5.0 0.5 - - 2.5 0.5 - - - - - - - - - - - 4.0 - 9.0 - - - - - - -
Parramatta (Baulkham Hills West) - - - 5.0 - - - 4.0 - - - - - - - - - - - - 6.5 0.5 9.5 - - - - - - -
Penrith Lakes AWS - - - 4.0 - - 0.2 0.2 - - - - - - - - - 0.2 - - - 0.2 9.0 - - - - - - -
Prospect Reservoir - - - 4.0 - - - 0.6 - - - - - - - - 0.1 - - - - 0.1 11.3 - - - - - - -
Richmond RAAF - - - 4.0 0.2 - - - - - - - - - - - - - - - - - - - - - - - - -
Seven Hills (Radio FM 103.2) - - - 4.5 0.5 - - 3.0 - - - - - - - - - - - - 3.0 0.5 11.0 - - - - - - -
Seven Hills (Collins St)


5.8


4.0











7.2
12.6






St Clair (Juba Close) - - - 4.0 - - - 2.0 - - - - - - - - - - - - - - 6.0 - - - - - - -
Toongabbie Bowling Club - - - 5.0 - - - 4.5 - - - - - - - - - - - - 4.0 - 12.0 - - - - - - -
Toongabbie Ck (Redbank Road (Toongabbee - - - 5.0 0.5 - - 5.0 - - - - - - - - - - - - 1.0 - 12.5 - - - - - - -
West Pennant Hills (Cumberland S F) - - - 4.5 0.5 - - 0.5 - - - - - - - - - - - - 8.5 0.5 6.0 - - - - - - -
Illawarra (68)123456789101112131415161718192021222324252627282930
Camden Airport AWS - - - 6.0 - - - 13.8 - - - - - - - - - - - - 1.4 - 13.0 - - - 0.2 - - -
Camden Valley Golf Resort - - - 1.0 - - - 1.0 - - - - - - - - - - - - - 1.0 4.0 - - - - - - -
Campbelltown (Kentlyn) - - - 6.0 - - - 8.0 - - - - - - - - - - - - 3.0 - 13.0 - - - - - - -
Campbelltown (Mount Annan) - - - 6.0 - - - 9.8 - - - - - - - - 0.2 - - - 4.2 - 14.4 - - - - - - -
Rossmore (South Creek) - - - 7.0 - - - 8.0 - - - - - - - - - - - - - - 11.0 1.0 - - - - - -

Notes

This statement has been prepared based on information available at 10 am on Thursday 1 October 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 Monitoring Officer
NSW Climate Services Centre
NSW Regional Office
Bureau of Meteorology
Phone (02) 9296 1555
Email climate.nsw@bom.gov.au