Monday, 3 September 2007 - Monthly Climate Summary for Sydney - Product code IDCKGC15L0

Hot August nights

Summary

  • record high average minimum temperatures
  • above average maximum temperatures
  • wet month, total of 152mm in top 25% of all August totals
  • below average sunshine hours

Rainfall

The total August rainfall of 152.2 mm at Sydney Observatory Hill was well above the historic August average1 of 81.5 mm.  It falls within the top 25% of all totals for August.  The majority of the rainfall occurred on 2 days, the 19th and 20th, when a low pressure trough developed off the NSW coast near Sydney. There were 13 rain days during the month, above the historic average of 10 rain days.  Rainfall distribution over the Sydney area for August was highest in the eastern and northern suburbs and lowest in the western suburbs. Totals ranged from 172.0 mm at Riverview Observatory to 35.4 mm at Campbelltown (Mt Annan) in the far south-west.

The Warragamba Dam catchment received light to moderate rainfall during August, with supply levels continuing to increase slowly.  Monthly totals over the catchment were generally in the 40-60mm range, except for the upper catchment where Goulburn received only 12mm in August.  Recent rainfall in Sydney's catchments can be found on the Sydney Catchment Authority web site at: http://www.sca.nsw.gov.au/dams/rainfall.html.

Temperature

The average maximum (daytime) temperature at Observatory Hill was 19.9C, which is well above the historic average1 temperature of 18.2C.  The elevated locations of Springwood (362 metres) and Terrey Hills (199 metres) recorded slightly cooler daytime temperatures: 18.4C and 18.9C respectively .  Towards the end of the month there were several days when temperatures rose into the mid 20's in Sydney. On the 27th and 28th there were 2 consecutive days above 27C at Observatory Hill;  this has happened only twice before in August, in 1885 and 1995.

This is now the 9th consecutive August with above average maximum temperatures.  In the past 16 years (since 1991) all but 2 Augusts in Sydney have recorded above average maximum temperatures.

Night-time temperatures were particularly mild throughout the Sydney metropolitan area with record high average minimum temperatures at Observatory Hill. The average minimum temperature of 11.7C was 2.3C above the historic average1 and the highest ever recorded for August. Warm overnight temperatures were partly a result of greater than average cloudiness during the month. The previous highest was 11.1C in 1987. Minimum temperatures were up to 6C cooler in far western suburbs, averaging 5.2C at Camden, however, they were still well above the historic August average.

The highest temperature at Sydney (Observatory Hill) during August was 27.7C on the 27th, while the lowest temperature was 6.9C on the 14th. Corresponding extremes in the Sydney area ranged from 27.9C at Penrith Lakes and Sydney Olympic Park on the 27th to -1.1C at Camden on the 8th.

Wind

There were 7 windy days as measured at Sydney Airport, compared to an average of 5. There was also a greater than usual occurrence of NW winds contributing to the above average temperatures experienced in the month. The highest wind gust reported was 65 km/h at Sydney Airport on the 19th.

Other phenomena

Hours of sunshine for August were the lowest since 1998.

Further information

Perry Wiles
Climatologist
NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1525
Email reqnsw@bom.gov.au

Extremes

Hottest day
Highest temperature
27.9 C at Penrith Lakes and Sydney Olympic Park on the 27th
Warmest days on average
Highest mean daily maximum temperature
20.3 C at Richmond RAAF
Coolest days on average
Lowest mean daily maximum temperature
18.4 C at Springwood Bowling Club
Coldest day
Lowest daily maximum temperature
10.8 C at Springwood Bowling Club on the 19th
Coldest night
Lowest temperature
-1.1 C at Camden Airport AWS on the 8th
Coolest nights on average
Lowest mean daily minimum temperature
5.5 C at Camden Airport AWS
Warmest nights on average
Highest mean daily minimum temperature
11.7 C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature
17.0 C at Sydney (Observatory Hill) on the 30th
Wettest overall
Highest total rainfall
172.0 mm at Riverview Observatory
Wettest day
Highest daily rainfall
126.0 mm at Riverview Observatory on the 20th
Highest wind gust
65 km/h at Sydney Airport on the 19th

Records

Record highest August mean daily minimum temperature
Mean daily minimum
temperature
for August 2007 (C)
Previous highest
for August
Normal for
August
Years of
record
Sydney (Observatory Hill) 11.7 11.1 in 1987 8.9 149
Sydney Airport 11.2 10.7 in 1998 68 7.9



Summaries

Summary statistics for August 2007
Maximum temperatures
for August
(C)
Minimum temperatures
for August
(C)
Rainfall
for August
(millimetres)
Mean for
August
2007
Diff
from
normal
Highest for
August
2007
Mean for
August
2007
Diff
from
normal
Lowest for
August
2007
Total for
August
2007
Normal
for
August
Rank of
August
2007
Fraction of
August
normal
Central Tablelands (S) (district 63)
Springwood Bowling Club 18.4 26.5 27th 8.0 3.0 7th 116.5 54.8 high 213%
Metropolitan (E) (district 66)
Parramatta North 20.2 +1.2 27.5 27th 9.3 +2.2 3.5 14th 113.8 57.8 high 197%
Sydney 19.9 +1.7 27.7 27th 11.7 +2.3 6.9 14th 152.2 81.5 high 186%
Terrey Hills AWS 18.9 25.8 28th 10.3 3.9 4th 116.2
Metropolitan (W) (district 67)
Richmond RAAF 20.3 +1.4 27.2 27th 7.8 +2.9 0.9 7th 84.2 45.8 high 183%
Illawarra (district 68)
Camden Airport AWS 19.9 +0.9 27.1 27th 5.5 +1.7 -1.1 8th 48.6 44.6 high 109%
Additional climate data for Sydney (Observatory Hill) for August 2007
 

August 2007

Normal for August

Number of rain days

 13

 10

Average sunshine hours per day*

 6.9

7.9

Average humidity at 3pm (%)

 54

50

Number of thunderstorms

0

1

Number of windy days*

7

5

* recorded at Sydney Airport


Notes

1Averages:  historic average temperatures for Observatory Hill and Richmond are based on the period 1961 to 1990 which is a convention of the World Meteorological Organisation.  Average temperatures for Parramatta are based on all available data, 1968 - 2006 and Camden 1972 - 2006.  Rainfall averages and extremes for Observatory Hill are based on all years of record 1859 - 2006.

This statement has been prepared based on information available at 8 am on Monday 3 September 2007. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Normals 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. For rainfall, it is sometimes better to use the median rather than the mean to indicate "normal" rain, but this has not been done here.

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, normal in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of normal shows how much rain has fallen this time as a percentage of the long-term mean.

Further information

Perry Wiles
Climatologist
NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1525
Email reqnsw@bom.gov.au