Monday, 3 December 2012 - Seasonal Climate Summary for ACT Monthly Summary - Product code IDCKGC15R0
Canberra in spring 2012: Cold nights, warm days
- Record number of cold nights
- Below average rainfall
- 9th warmest maximum temperatures on record
- 7th coldest minimum temperatures on record
Rainfall - Close to average, but few wet days
Canberra Airport recorded a total of 137.6 mm during spring, below the historical average of 178.8 mm. September and October recorded close to normal rainfall, while November was drier than normal. There were 20 rain days at Canberra, which is below the average of around 30 days, and only one day recorded more than 25 mm of rain.
The most significant spring rainfall event for Canberra was for the period 11 and 12 October, associated with a surface trough and East Coast Low that developed off the south coast of NSW. Canberra Airport recorded a 48 hour total of 56.6 mm to 9am on the 12th, the wettest October event since 83.8 mm fell over two days in October 1976. The wettest spring day anywhere in the ACT occurred on the 29th of September, with 48.8 mm at Mt Ginini as a cold front and associated thunderstorms passed through the ACT..
Temperature - Hot days and cold nights in the ACT
The average maximum temperature at Canberra Airport during spring was 21.4 °C, which is 2 °C above the historical average of 19.4 °C and 9th warmest on record. Each of the three spring months experienced warmer than average temperatures, with September being particularly warm, experiencing its 6th warmest September on record.
There were four days that exceeded 30 °C during spring, close to the average of about 3, with temperatures reaching 35.1 °C on the 30th, the warmest spring day since 2009. All of these hot days occurred over the last week of spring, associated with a significant hot spell that affected much of NSW and the ACT. This hot spell, combined with generally clear conditions and low rainfall during spring, resulted in the warmer daytime temperatures.
The mean minimum temperature at Canberra Airport was 4.8 °C, which is 1.2 °C below the historical average of 6.0 °C and 7th coolest on record. The coldest night was recorded on the first day of spring, where Canberra dropped to -6.8 °C. This is the coldest September night on record at Canberra, and was followed by two further nights below -4 °C. Minimum temperatures steadily warmed during spring, with November recording slightly above average overnight temperatures.
There were 18 nights that reported 0 °C or cooler, which is well above the historical average of 7 - 8 nights and the highest number of cold spring nights on record. There were also 9 nights which were -2 °C or colder, again well above the average of 2 - 3 nights.
With the warm daytime temperatures and generally cooler overnight temperatures, the mean daily temperature range (difference between mean daily minimum and maximum temperatures) was very much above average. For spring in 2012, the mean daily temperature range was 16.6 °C, which is the 2nd highest on record, behind 2006 (16.9 °C).
Winds were predominantly from the W - NW at Canberra Airport, accounting for 57% of 3pm winds, slightly below the usual frequency of 59% from this direction in spring. The maximum wind gust recorded at Canberra was 93 km/hr on the 16th October, which was also the equal highest wind gust anywhere in the ACT, along with 93 km/hr at Mt Ginini on the 28th September.
The East Coast Low on the south coast of NSW was the major feature for spring 2012, bringing heavy rain and very cold temperatures to Canberra on the 11th and 12th October. This event also resulted in snow falls across the ACT; in nearby Goulburn this was the first report of spring snow since 22 November 1996.
|Extremes in spring 2012|
35.1 °C at Canberra Airport on 30 Nov|
|Warmest days on average||21.4 °C at Canberra Airport|
|Coolest days on average||
12.6 °C at Mount Ginini AWS|
|Coldest day||-1.5 °C at Mount Ginini AWS on 7 Sep|
-6.8 °C at Canberra Airport on 1 Sep|
|Coolest nights on average||2.7 °C at Mount Ginini AWS|
|Warmest nights on average||
5.6 °C at Tuggeranong (Isabella Plains) AWS|
18.5 °C at Tuggeranong (Isabella Plains) AWS on 30 Nov|
|Warmest on average overall||
13.5 °C at Tuggeranong (Isabella Plains) AWS|
|Coolest on average overall||7.6 °C at Mount Ginini AWS|
|Wettest overall||214.4 mm at Mount Ginini AWS|
|Wettest day|| 48.8 mm at Mount Ginini AWS on 29 Sep|
|Highest wind gust||
93 km/h at Mount Ginini AWS on 28 Sep|
93 km/h at Canberra Airport on 16 Oct
|Summary statistics for spring 2012|
|Canberra Airport||21.4||+2.0||35.1||30 Nov||4.8||-1.2||-6.8||1 Sep||137.6||178.8||77%|
|Mount Ginini AWS||12.6||25.1||29 Nov||2.7||-6.2||1 Sep||214.4|
|Tuggeranong (Isabella Plains) AWS||21.4||34.5||29 Nov||5.6||-5.5||1 Sep||138.4|
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).
An 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 Monday 3 December 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 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..