Wednesday, 2 September 2009 - Monthly Climate Summary for Canberra area - Product code IDCKGC2xx0

A warm August 2009 for the ACT

  • 9th warmest August on record
  • Above average minimum temperatures
  • Warmest August night on record at Canberra Airport on the 24th (12°C)
  • Below average rainfall

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

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Rainfall

Canberra Airport recorded a total rainfall of 37.4 mm during the month, which is slightly below the historic average of 46.0 mm. However, the number of rain days was above average at 14 days (August average 11 days), which is the highest since 1990 (when 19 rain days).

Prevailing high pressure systems over NSW and lack of any significant rain producing systems contributed towards the below average rainfall in the ACT. The majority of rain occurred during three main events, a low pressure system on the 12th and cold fronts on the 22nd and 30th.

Monthly totals for August ranged from a high of 142.8 mm at Corin Dam in the highlands SW of Canberra to a low of 21.8 mm at Watson (Racecourse).

Temperatures

The mean maximum (daytime) temperature at Canberra Airport was 14.5°C, which is 1.5°C above the historical average of 13.0°C. This is the 9th warmest August in the 71 year record for Canberra. The highest mean maximum temperature in the ACT was 14.7°C at Tuggeranong, with this location also recording the warmest day of the month of 19.1°C on the 23rd. Prevailing NW winds and the lack of any significant cool changes, contributed towards the mild daytime temperatures.

Nights were generally mild, with the mean minimum temperatures at Canberra Airport of 2.4°C, 1.4°C above the August average of 1.0°C. On the 24th, Canberra Airport recorded its highest minimum temperature on record for August with 12.0°C which is 11°C above the historic August minimum. There were only 11 frosts during the month (minimum temperature below zero deg) compared to the normal 19 frosts for August. The lowest temperature in Canberra suburbs was −5.5°C at Tuggeranong AWS on the 9th.

The mild temperatures were mainly due to prevailing N-W winds throughout the month, bringing warm dry air to much of NSW and the ACT.

Some sites had their warmest August night (highest daily minimum temperature) on record.

Wind

The prevailing wind direction over Canberra during the afternoons was W-NW for around 87% of the time, well above the average frequency of about 63% for this direction in August. The prevailing wind direction during the mornings was N-NW at about 45% of the time, compared to the usual 32% from this direction. Three days of strong wind were recorded at Canberra Airport on the 7th, 25th and 30th of August. The highest wind gusts in the ACT were recorded on the 25th, with 109 km/h at Mt Ginini AWS and 89 km/h at Canberra Airport.

Other phenomena

Two thunderstorms occurred in the Canberra region, on the 11th and 29th of August, the former associated with small hail. The frequency of fog was slightly below average, with only 3 fogs reported at Canberra Airport compared to the normal frequency of around 5 days of fogs. The amount of sunshine averaged 7.2 hours per day, which is slightly above the historic average for August of 7.0 hours.

Further information

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

Extremes for the ACT

Hottest day
Highest temperature		 19.1°C at Tuggeranong AWS on the 23rd
Warmest days on average
Highest mean daily maximum temperature		 14.7°C at Tuggeranong AWS
Coolest days on average
Lowest mean daily maximum temperature		 14.5°C at Canberra Airport
4.4°C at Mount Ginini AWS
Coldest day
Lowest daily maximum temperature		 10.0°C at Tuggeranong AWS on the 25th
−2.4°C at Mount Ginini AWS on the 25th
Coldest night
Lowest temperature		−5.5°C at Tuggeranong AWS on the 9th
−6.3°C at Mount Ginini AWS on the 8th and 26th
Coolest nights on average
Lowest mean daily minimum temperature		 1.6°C at Tuggeranong AWS
−1.5°C at Mount Ginini AWS
Warmest nights on average
Highest mean daily minimum temperature		 2.4°C at Canberra Airport
Warmest night
Highest daily minimum temperature		 12.0°C at Canberra Airport on the 24th
Wettest overall
Highest total rainfall		 142.8 mm at Corin Dam
Driest overall
Lowest total rainfall		 21.8 mm at Watson (Racecourse)

Wettest Day
Highest daily rainfall

 40.2 mm at Corin Dam on the 22nd
Highest wind gust
 89 km/h at Canberra Airport on the 25th
109 km/h at Mount Ginini AWS on the 25th

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Records

Record highest August daily minimum temperature
Highest daily minimum
temperature
in August 2009 (°C) 		Previous highest
for August		 Years of
record		 Average for
August
Canberra Airport 12.0 on the 24th 11.4 on the 18th in 1988 71 1.0


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Summaries for the ACT

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

Summary statistics for August 2009
Maximum temperatures
for August
(°C)		 Minimum temperatures
for August
(°C)		 Rainfall
for August
(millimetres)
Mean for
August
2009		 Diff
from
average		 Highest for
August
2009		 Mean for
August
2009		 Diff
from
average		 Lowest for
August
2009		 Total for
August
2009		 Average
for
August		 Rank of
August
2009		 Fraction of
August
average
Canberra Airport 14.5 +1.5 19.0 23rd 2.4 +1.4 −4.9 9th 37.4 46.0 average 81%
Mount Ginini AWS 4.4   10.3 20th −1.5   −6.3 8th 103.8
Tuggeranong 14.7 +0.5 19.1 23rd 1.6 +0.9 −5.5 9th 31.8 49.5 average 65%

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Notes

This statement has been prepared based on information available at noon on Wednesday 2 September 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

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