Tuesday, 3 January 2012 - Annual Climate Summary for ACT Monthly Summary - Product code IDCKGC15R0
Canberra in 2011: A normal year for the ACT
- Below average rainfall.
- Close to average temperatures.
- Most cold nights since 1982.
Canberra Airport recorded 580.1 mm of rain during 2011, slightly below the historical average of 614.4 mm. The rain fell over 118 days, the most since 1989, with five days exceeding 25 mm and one reaching 50 mm, normal for Canberra. Throughout the ACT, the highest annual total was 1209.2 mm at Mt Ginini, while Tuggeranong reached 899.8 mm. Tuggeranong was drier than 2010 (1077.2 mm), but otherwise this was its wettest year since records began in 1996.
Most months during 2011 had below average rainfall at Canberra, particularly during autumn, which was the 12th driest on record. However, February recorded more than double the historical average to be the 7th wettest on record. Most of this was due to a significant rain event across NSW in the first week of the month, with daily falls of over 40 mm recorded at the Airport on both the 3rd and 5th, and ACT totals reaching 103 mm at Mt Ginini and 83.6 mm at Tuggeranong on the 3rd. Rainfall also increased towards the end of the year as a weak La Niña developed, with November the 8th wettest on record for Canberra. Much of this was due to a low pressure trough that brought 45 mm to Canberra Airport on November 6th, reaching 91.6 mm at Tuggeranong.
Temperatures in Canberra were close to average during 2011, with maximums 0.6 °C above average and minimums 0.2 °C below average. 26 days during 2011 exceeded 30 °C, slightly below the historical average of 32 days and the fewest since 25 days in 1999. There were also 79 days with minimums of 0 °C or lower, the 8th highest number of cold nights on record for Canberra, and the most since 84 cold nights in 1982.
Maximum temperatures were close to average between January and May, resulting in the coolest autumn since 1995. Days warmed over subsequent months associated with low rainfall and clear conditions, with the warmest winter on record followed by the 9th warmest spring. Temperatures were particularly warm during August, September and November, all of which had days more than 2 °C above average. Temperatures cooled during the start of summer, with the 5th coldest December on record for Canberra associated with cloudy conditions and a lack of hot days.
Minimum temperatures during 2011 were the coolest for Canberra since 1996, following an extended spell of warm nights over the last decade. Minimums were warm at the start of the year, with the 6th warmest January on record and both February and March more than 1 °C above average. Nights were very cold during the rest of Autumn, including the 4th coldest May nights on record, followed by closer to average temperatures during winter and spring and cooler conditions during December. A cold snap occurred towards the end of July, with three consecutive nights below -6 °C between the 28th and 30th, the first such period since 15-17 August 1994. The coldest night reached -8 °C on the 29th, the coldest night in Canberra since -8.5 °C was recorded on August 9 1994.
Prevailing wind directions at Canberra Airport during 2011 were N-W, forming 41% of 9am winds and 62% of 3pm winds, similar to the average distributions. The highest wind gusts at Canberra Airport were 83 km/hr on July 5 and September 29, with the highest wind recorded anywhere in the ACT reaching 107 km/hr at Mt Ginini on September 20.
There were 43 thunderstorms reported across the ACT during 2011. Hail was reported for three storms during the year, with reports of golf ball sized hail associated with a severe storm on January 5.
|Extremes in 2011|
|Hottest day||37.6 °C at Tuggeranong (Isabella Plains) AWS on 31 Jan|
|Warmest days on average||20.3 °C at Canberra Airport|
|Coolest days on average||10.8 °C at Mount Ginini AWS|
|Coldest day||-3.1 °C at Mount Ginini AWS on 11 May|
|Coldest night||-8.2 °C at Tuggeranong (Isabella Plains) AWS on 29 Jul|
|Coolest nights on average||3.2 °C at Mount Ginini AWS|
|Warmest nights on average||7.2 °C at Tuggeranong (Isabella Plains) AWS|
|Warmest night||23.0 °C at Tuggeranong (Isabella Plains) AWS on 2 Feb|
|Warmest on average overall||13.6 °C at Tuggeranong (Isabella Plains) AWS|
|Coolest on average overall||7.0 °C at Mount Ginini AWS|
1382.0 mm at Mount Ginini AWS|
899.8 mm at Tuggeranong (Isabella Plains) AWS
890.2 mm at Tharwa General Store
|Wettest day||102.2 mm at Mount Ginini AWS on 3 Feb|
|Highest wind gust||107 km/h at Mount Ginini AWS on 20 Sep|
|Summary statistics for 2011|
|Canberra Airport||20.3||+0.6||37.5||31 Jan||6.3||-0.2||-8.0||29 Jul||580.1||614.4||average||94%|
|Mount Ginini AWS||10.8||28.0||31 Jan||3.2||-6.6||15 Jul||1382.0|
|Tuggeranong (Isabella Plains) AWS||20.1||37.6||31 Jan||7.2||-8.2||29 Jul||899.8|
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 Annual 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 8 am on Tuesday 3 January 2012. 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
(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.