Monday, 1 September 2008 - Monthly Climate Summary for Sydney - Product code IDCKGC25L0

Sydney in August 2008
Cold end to winter

Summary

  • Rainfall below average
  • Lowest average August maximum temperatures since 1989
  • First August with mean maximum temperatures below the long term average since 1998
  • Lowest mean August minimum temperature since 1951

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

 

Rainfall

Sydney recorded below average rainfall for the month of August with Observatory Hill recording 44.2 mm compared with the historic August average1 of 81.7 mm. There were 7 rain days during August which is below the average of 10. Most of the rain recorded fell on two days with 20.8 mm recorded on the 23rd in association with a low pressure system which formed off the coast and then 12 mm on the 31st from a rain bearing cloud band associated with a trough and frontal system that brought good falls to much of NSW right at the end of the month.

Most areas in Sydney received between 10 and 50 mm over the month, while a few generally more coastal sites received over 50mm. The highest monthly total was 80.0 mm at Randwick in the eastern suburbs.

Between 20 and 60mm of rain was recorded over the Warragamba Dam catchment during August. Recent rainfall in Sydney's drinking water catchments can be found on the Sydney Catchment Authority web site http://www.sca.nsw.gov.au/dams/rainfall.html

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Temperature

As for most of NSW, August was a particularly cool month for Sydney, with both maximum and minimum temperatures below the historic averages across the Sydney basin. The mean maximum temperature at Observatory Hill of 17.3°C was -0.5°C below the historic August average1. This is the first August with mean maximum temperatures below the long term average since 1998. It is the coldest average August maximum temperatures since 1989 when the average was also 17.3 °C and since 1978 for a cooler August (17.1 °C). The cool temperatures were largely a result of an unusually strong and persistent high pressure system in the Southern Ocean off the south west of Western Australia directing southerly to south-westerly winds over the eastern Australian mainland for much of the month, pushing cool air from the Southern Ocean well north of usual.

With the cold air mass over eastern Australia combining with below average rainfall and less cloud cover, overnight temperatures were particularly cold across Sydney. The mean minimum temperature at Observatory Hill was 8.1°C, below the historical mean for July of 8.3°C (July is usually Sydney's coldest month), and -0.8°C below the historic average1 for August. This was the lowest mean August minimum temperature since 1951 when the mean minimum was also 8.1°C and since 1943 for a cooler August mean minimum (7.6 °C).

Some sites had their coldest August day (lowest maximum temperature) on record.

Some sites had their lowest August mean daily maximum temperature on record.

Some sites had their lowest August mean daily maximum temperature for at least 20 years.

Some sites had their lowest August mean daily minimum temperature on record.

Some sites had their lowest August mean daily minimum temperature for at least 20 years.

Wind

In August Sydney (Fort Denison) experienced a greater than usual frequency of winds from the south-west to south-east during the afternoons with around 39% of all winds from this direction, compared to the average frequency of about 29%. The corresponding figure at Sydney Airport was 45%, compared to a average frequency of 40%. This reflects the impact of the high pressure system mentioned above directing south to south-westerly winds over eastern Australia for a significant part of the month. The highest wind gust in the greater Sydney area was 94 km/h at Penrith Lakes AWS on 2 Aug. Strong winds were observed at Sydney Airport on 5 days which is close to average for August.

Other phenomena

Three thunderstorms were observed in the vicinity of Sydney Airport area in August compared to a long term average of 1.4. Average August sunshine of 7.5 hours per day was close to the historic average.

Further information

NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email reqnsw@bom.gov.au

Extremes for the Sydney area

Hottest day
Highest temperature
22.2 °C at Richmond RAAF on the 1st
Warmest days on average
Highest mean daily maximum temperature
17.9 °C at Parramatta North
Coolest days on average
Lowest mean daily maximum temperature
16.0 °C at Terrey Hills AWS
Coldest day
Lowest daily maximum temperature
10.5 °C at Terrey Hills AWS on the 22nd
Coldest night
Lowest temperature
-2.9 °C at Richmond RAAF on the 19th
Coolest nights on average
Lowest mean daily minimum temperature
1.7 °C at Richmond RAAF
Warmest nights on average
Highest mean daily minimum temperature
8.1 °C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature
12.8 °C at Parramatta North on the 31st
Wettest overall
Highest total rainfall
80.0 mm at Randwick
Driest overall
Lowest total rainfall
14.0 mm at St Clair
Wettest day
Highest daily rainfall
40.6 mm at Berowra on the 31st
Highest wind gust
94 km/h at Penrith Lakes AWS on 2 Aug

Records for the Sydney area

Record lowest August daily maximum temperature
Lowest daily maximum
temperature
in August 2008 (°C)
Previous lowest
for August
Years of
record
Normal for
August
Camden Airport AWS 11.2 on the 22nd 12.0 on the 4th in 1986 32 19.0


Record lowest August mean daily maximum temperature
Mean daily maximum
temperature
for August 2008 (°C)
Previous lowest
for August
Years of
record
Normal for
August
Camden Airport AWS
17.5
17.6 in 1998 32 19.0

Lowest August mean daily maximum temperature for at least 20 years
Mean daily maximum
temperature
for August 2008 (°C)
Most recent lower
for August
Years since
lower
Normal for
August
Sydney (Observatory Hill)
17.3
17.1 in 1978 30 17.8


Record lowest August mean daily minimum temperature
Mean daily minimum
temperature
for August 2008 (°C)
Previous lowest
for August
Years of
record
Normal for
August
Parramatta North
5.5
5.8 in 1997 42 7.1

Lowest August mean daily minimum temperature for at least 20 years
Mean daily minimum
temperature
for August 2008 (°C)
Most recent lower
for August
Years since
lower
Normal for
August
Sydney (Observatory Hill)
8.1
8.1 in 1951 57 8.9


Summaries for the Sydney area

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

Summary statistics for August 2008
Maximum temperatures
for August
(°C)
Minimum temperatures
for August
(°C)
Rainfall
for August
(millimetres)
Mean for
August
2008
Diff
from
normal
Highest for
August
2008
Mean for
August
2008
Diff
from
normal
Lowest for
August
2008
Total for
August
2008
Normal
for
August
Rank of
August
2008
Fraction of
August
normal
Sydney (Observatory Hill) 17.3 -0.5 21.5 26th 8.1 -0.8 5.3 19th 44.2 81.7 average 54%
Parramatta North 17.9 -1.1 21.6 26th 5.5 -1.6 1.8 19th 29.2 57.2 average 51%
Richmond RAAF 17.5 -1.3 22.2 1st 1.7 -2.8 -2.9 19th 27.8 37.0 average 75%
Camden Airport AWS 17.5 -1.5 22.1 26th 2.9 -1.0 -2.3 10th 38.8 44.5 average 87%
Terrey Hills AWS* 16.0   20.2 26th 6.3   3.0 18th 54.8
Springwood Bowling Club* 16.1   21.5 26th 5.6   2.6 9th 23.0 54.5 average 42%

* new stations, no historic average temperatures available and no historic average rainfall available for Terrey Hills

Notes

This statement has been prepared based on information available at 9 am on Monday 1 September 2008. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

1Averages: historic rainfall and temperature averages are based on all available data.

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 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average ("normal") 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, 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

NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email reqnsw@bom.gov.au