ACT in autumn 2011: Cool days and cold nights in Autumn 2011

  • 12th driest Autumn on record
  • Equal 6th coldest minimum temperatures on record
  • Coolest maximum temperatures since 1995

Rainfall

Canberra Airport recorded 62.2 mm of rain during Autumn, well below the historical average of 141.2 mm and the 12th driest Autumn on record. All three months recorded below average rainfall, with the majority of rain falling during March and very much below average rainfall in both April and May. The maximum daily rainfall was just 13.4 mm on March 11, the lowest since Autumn 2004. However, rainfall varied throughout the ACT, with Tharwa General Store recording 70 mm on March 12, its wettest Autumn day since March 1989.

The return to drier conditions is associated with the breakdown of La Niña conditions following March, while Canberra was generally sheltered from the predominantly coastal rainfall in NSW during April and May.

Temperature

The average maximum temperature at Canberra Airport during Autumn was 19.6 °C, below the historical average of 20 °C and the coldest Autumn since 19.2 °C in May 1995. This is the first Autumn since 1996 to have below average maximum temperatures, which is primarily due to cloudy conditions during March and a lack of warm days above 25 °C during the early part of the season.

Minimum temperatures averaged 5.7 °C, 1.1 °C below the historical average, the coolest Autumn nights since 5.6 °C in 1984 and the equal 6th coolest on record. Temperatures were coolest towards the end of the season, with well above average minimums during March but below average temperatures associated with the clearer conditions during April and May. Mean temperatures were consequently 12.7 °C, the coolest since 1994 and the equal 9th coolest on record.

Wind

Winds were predominately northwesterly during Autumn, forming 41% of 3pm winds at Canberra Airport, slightly above the average frequency for Autumn.

Other phenomena

Four thunderstorms were reported in the ACT region, primarily during March.

Further information

Media
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Extremes in autumn 2011
Hottest day 29.1 °C at Canberra Airport on 13 Mar
Warmest days on average 19.6 °C at Canberra Airport
Coolest days on average 10.4 °C at Mount Ginini AWS
Coldest day -3.1 °C at Mount Ginini AWS on 11 May
Coldest night -6.9 °C at Canberra Airport on 15 May
Coolest nights on average 3.2 °C at Mount Ginini AWS
Warmest nights on average 6.6 °C at Tuggeranong (Isabella Plains) AWS
Warmest night 17.9 °C at Canberra Airport on 14 Mar
Warmest on average overall 13.0 °C at Tuggeranong (Isabella Plains) AWS
Coolest on average overall 6.8 °C at Mount Ginini AWS
Wettest overall 196.6 mm at Mount Ginini AWS
Wettest day 70.0 mm at Tharwa General Store on 12 Mar
Highest wind gust 80 km/h at Mount Ginini AWS on 13 May


Summary statistics for autumn 2011
Maximum temperatures
for autumn
(°C)
Minimum temperatures
for autumn
(°C)
Rainfall
for autumn
(millimetres)
Mean for
autumn
2011
Diff
from
average
Highest for
autumn
2011
Mean for
autumn
2011
Diff
from
average
Lowest for
autumn
2011
Total for
autumn
2011
Average
for
autumn
Rank of
autumn
2011
Fraction of
autumn
average
Canberra Airport 19.6 -0.4 29.1 13 Mar 5.7 -1.1 -6.9 15 May 62.2 141.2 low 44%
Mount Ginini AWS 10.4   19.7 13 Mar 3.2   -6.4 12 May 196.6
Tuggeranong (Isabella Plains) AWS 19.3   29.0 13 Mar 6.6   -5.7 15 May 114.2

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.

A Seasonal 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 10 am on Wednesday 1 June 2011. 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

Media
(03) 9669 4057
Enquiries