ACT in September 2010: Equal foggiest September on record

  • Foggiest September since 1951 (= record)
  • Above average rainfall - wettest September since 2005
  • Warm nights, warm days

Rainfall

Canberra recorded a total rainfall of 65.8mm during September, which is above the historical average1 of 52.2mm. This is the wettest September since 2005 (100.6mm) and slightly abover the September 2009 total of 57.6mm. The rain fell over 8 days (average 10), with the most significant on the 4th and 5th (49.6mm) associated with a deep low pressure system over South Australia. A complex low pressure system that crossed the ACT and NSW brought some light falls to the area around the 15th of the month, which amounted to about 10mm for Canberra. The highest daily rainfall at Canberra was 26.0mm recorded on the 5th, whilst the highest daily rainfall for the ACT was 68.6mm recorded at Mt Ginini on the 5th.

Temperature

Canberra recorded an average maximum temperature of 16.3°C during September, which is close to the historical average of 16.2°C. This is the coldest September since 2005 (16.3°C) for Canberra for average day time temperatures. The warmest day at Canberra was 21.2°C on the 21st, and the coolest day was 12.4°C on the 5th. Across the ACT, the warmest day was 21.6°C at Tuggeranong on the 26th, and the coolest day was 0.4°C at Mt Ginini on the 6th.

Canberra recorded an average minimum temperature of 4.0°C during September, which is above the historical average of 3.2°C, but below September 2009's average of 4.3°C. 5 nights dropped below freezing, which is slightly less than the historical average of 6 nights. The coolest night at Canberra was -1.9°C on the 30th, and for the ACT the coolest was -5.2°C at Mt Ginini on the 7th.

The mean temperature (average of the maximum and minimum temperature) for September was 10.1°C, which is slightly above the historical average of 9.7°C. This is the coolest September since 1995 for average mean temperatures.

Wind

Canberra Airport was dominated by west to northwesterly winds in September, forming 56% of winds (during the mornings), and 53% during the afternoons. 6 strong wind days were reported (winds >= 40km/hr), which is about average for this time of year.

Other phenomena

11 fogs were observed at Canberra Airport during September, well above the histroical average of 4. This equals the foggiest September on record (1951), and is the foggiest September since 1951. Canberra averaged 7.8 hours of sunshine per day, slightly above the historical average of 7.7 hours. 7 frosts were observed (average 13). No thunderstorms were observed during the month.

Further information

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Extremes in September 2010
Hottest day 21.6 °C at Tuggeranong (Isabella Plains) AWS on the 26th
Warmest days on average 16.7 °C at Tuggeranong (Isabella Plains) AWS
Coolest days on average 16.2 °C at Canberra Airport Comparison
Coldest day 0.4 °C at Mount Ginini AWS on the 6th
Coldest night -5.2 °C at Mount Ginini AWS on the 17th
-5.2 °C at Mount Ginini AWS on the 29th
Coolest nights on average 4.0 °C at Canberra Airport
Warmest nights on average 4.6 °C at Canberra Airport Comparison
Warmest night 10.5 °C at Tidbinbilla Nature Reserve on the 28th
Wettest overall 123.4 mm at Mount Ginini AWS
Wettest day 68.6 mm at Mount Ginini AWS on the 5th
Highest wind gust 109 km/h at Mount Ginini AWS on the 4th




Summary statistics for September 2010
Maximum temperatures
for September
(°C)
Minimum temperatures
for September
(°C)
Rainfall
for September
(millimetres)
Mean for
September
2010
Diff
from
average
Highest for
September
2010
Mean for
September
2010
Diff
from
average
Lowest for
September
2010
Total for
September
2010
Average
for
September
Rank of
September
2010
Fraction of
September
average
Southern Tablelands (Goulburn-Monaro) (district 70)
Canberra Airport 16.3   21.2 21st 4.0   -1.9 30th 65.8
Canberra Airport Comparison 16.2 0.0 21.4 21st 4.6 +1.4 -1.0 30th - 52.0 low 65%
Mount Ginini AWS 8.3   17.4 21st -0.2   -5.2 17th 123.4
Tidbinbilla Nature Reserve 16.1 +0.6 20.5 21st 4.7 +1.0 -1.0 30th 121.4 91.7 high 132%
Tuggeranong (Isabella Plains) AWS 16.7   21.6 26th 4.1   -2.0 30th 99.0

 

Notes

As of March 2010, the official station for Canberra is 70351 'Canberra Airport'. Averages from the previous site, 70014 Canberra Airport Comparison, are used for comparisons (all years of record).

A Monthly Climate Summary is prepared to list the main features of the weather in ACT Monthly Summary using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at 9 am on Friday 1 October 2010. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

1Averages 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

Media
(03) 9669 4057
Enquiries