Tuesday, 1 June 2010 - Seasonal Climate Summary for ACT Monthly Summary - Product code IDCKGC15R0

ACT in Autumn 2010
Wettest Autumn for twenty years

  • Wettest Autumn since 1990
  • 8 days with rain above 10mm, seventh highest on record
  • Above average maximum and minimum temperatures

An archive of previous seasonal summaries for ACT Monthly Summary is also available, as are summaries for other states and many other climate summaries and diagnostics.

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Rainfall

Rainfall varied significantly in Canberra throughout autumn, with very high totals in March and May offset by well below average rainfall during April. The total rainfall at Canberra Airport during the season was 186.8mm, which is the highest Autumn rainfall since 1990 (226mm) and the 19th wettest on record. This is the first Autumn since 2000 to exceed the average May rainfall of 141.2mm

This rain fell over 24 days, close to the Autumn average of 22. Of these, eight days exceeded 10mm, double the average of 4.3 such days. This is the seventh highest amount of high rain days in Autumn on record, and the highest since 8 such days were recorded in Autumn 1990. Three days also recorded rainfall above 20mm, associated with the passage of troughs on March 8 and 31, and an East Coast Low on May 30.

The wettest location in the ACT during Autumn was 259.4mm at Mt Ginini AWS, followed by 239.4mm at Tidbinbilla in the suburbs. The highest rainfall recorded on any single day was associated with a low pressure trough on the 8th of March, which brought 35mm at Canberra Airport, reaching 78mm at Mt Ginini and 68mm at Tidbinbilla on the same day.

Some sites had their highest total autumn rainfall for at least 20 years.

Temperature

The mean temperature at Canberra Airport during May was 14.1°C, which was 0.7°C above the historical average of 13.4°C. This was associated with both above average maximum and minimum temperatures through the season, with particularly warm maximum temperatures during April and May.

Maximum temperatures at Canberra Airport averaged 20.8°C during Autumn, 0.8°C above the historical average of 20°C. This was associated with well above average maximums in April and May, while temperatures were just 0.1°C above average during March. However, this is the coolest autumn for maximum temperatures since 2003 (20.4°C). Temperatures were warmest at Tuggeranong, with 20.9°C, while the hottest day recorded during the season was 29.3°C at Tuggeranong on March 26. These warm conditions were associated with generally northerly winds and the clear and sunny conditions throughout the month associated with the passage of high pressure systems, despite the cooling effects of rain systems in March and late May.

Minimum temperatures averaged 7.4°C at canberra Airport during Autumn, 0.6°C above the historical average of 6.8°C. This was associated with well above average overnight temperatures in March and April, although nights in May were 0.1°C below average. Overnight minimums were warmer at Tidbinbilla, averaging 7.6°C, with the lowest temperature recorded anywhere in Canberra -4.8°C at Mt Ginini AWS on the 12th of May. The lowest in the Canberra metropolitan area was -3.7°C at Canberra Airport on 13 May.

Wind

Winds were predominantly northerly to westerly during autumn, forming 64% of 3pm windflow, significantly above the Autumn average of approximately 50% from this direction, contributing to the warm conditions. No strong wind days were reported at Canberra Airport, with the maximum wind gust just 61km/h on April 11. Higher winds were experienced at Mt Ginini (elevation 1760m), which recorded the maximum wind gust anywhere in Canberra of 87 km/h on May 30, associated with an East Coast Low.

Other phenomena

Canberra Airport averaged 7.6 hours of sunshine during Autumn, which is above the historical average of 7.1 hours per day. Sunshine was highest in April, which recorded 8.2 hours per day. Three thunderstorms were reported during the season, with no significant dust storms.

Further information

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

Extremes

Hottest day
Highest temperature		 29.3 °C at Tuggeranong (Isabella Plains) AWS on 26 Mar
Warmest days on average
Highest mean daily maximum temperature		 20.9 °C at Tuggeranong (Isabella Plains) AWS
Coolest days on average
Lowest mean daily maximum temperature		 19.8 °C at Tidbinbilla Nature Reserve
Coldest day
Lowest daily maximum temperature		 1.4 °C at Mount Ginini AWS on 5 May
Coldest night
Lowest temperature		 -4.8 °C at Mount Ginini AWS on 12 May
-3.7 °C at Canberra Airport on 13 May
Coolest nights on average
Lowest mean daily minimum temperature		 7.4 °C at Canberra Airport
7.4 °C at Tuggeranong (Isabella Plains) AWS
Warmest nights on average
Highest mean daily minimum temperature		 7.6 °C at Tidbinbilla Nature Reserve
Warmest night
Highest daily minimum temperature		 19.2 °C at Canberra Airport on 7 Mar
Wettest overall
Highest total rainfall		 259.4 mm at Mount Ginini AWS
239.4 mm at Tidbinbilla Nature Reserve
Wettest day
Highest daily rainfall		 78.0 mm at Mount Ginini AWS on 8 Mar
68.0 mm at Tidbinbilla Nature Reserve on 8 Mar
Highest wind gust
 87 km/h at Mount Ginini AWS on 30 May
65 km/h at Tuggeranong (Isabella Plains) AWS on 30 May

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Records

Highest total autumn rainfall for at least 20 years
Total rainfall
for autumn 2010 (mm) 		Most recent higher
for autumn		 Years since
higher		 Average for
autumn
Canberra Airport 186.8 226.0 in 1990 20 141.2


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Summaries

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

Summary statistics for autumn 2010
Maximum temperatures
for autumn
(°C)		 Minimum temperatures
for autumn
(°C)		 Rainfall
for autumn
(millimetres)
Mean for
autumn
2010		 Diff
from
average		 Highest for
autumn
2010		 Mean for
autumn
2010		 Diff
from
average		 Lowest for
autumn
2010		 Total for
autumn
2010		 Average
for
autumn		 Rank of
autumn
2010		 Fraction of
autumn
average
Canberra Airport 20.8 +0.8 29.1 26 Mar 7.4 +0.6 -3.7 13 May 186.8 141.2 high 132%
Tidbinbilla Nature Reserve 19.8 +0.4 27.5 28 Mar 7.6 +0.9 0.0 7 May 239.4 199.1 high 120%
Tuggeranong 20.9   29.3 26 Mar 7.4   -3.2 13 May 188.0

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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.

This statement has been prepared based on information available at 10 am on Tuesday 1 June 2010. 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

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