Canberra in September 2012: Hot days and cold nights

  • Equal 6th warmest September on record for maximums
  • Coldest September minimums since 1994
  • Coldest September night on record

Rainfall - Wettest September day since 2002

Canberra Airport recorded 41.4 mm of rainfall during September, below the historical average of 52 mm. The rain fell over 9 days, close to the September average of 10 days, but only one day recorded more than 5 mm (average 3 days), the fewest since 2007. Almost all of the rain fell as a cold front produced rain and thunderstorms in the ACT on the 29th, with up to 48.8 mm at Mt Ginini, while Canberra Airport recorded its wettest September day since 2002 with 28.4 mm.

Temperature - Warm days and cold nights

The average maximum temperature at Canberra Airport was 18 °C, 1.8 °C above the historical average. This is the equal 6th warmest September on record for Canberra, but slightly cooler than 18.2 °C in 2011. The warm days were associated with generally dry, sunny conditions during the month; eighteen days reached 18 °C or higher, the third highest on record for Canberra.

In contrast, the average minimum temperature was 1.6 °C, 1.7 °C below the historical record and the coldest Semptember since 1994. The cool nights were also associated with clear conditions, with eight nights falling below -2 °C during the month, the second highest on record following 9 cold nights in 1971 and 1946 (average 2 nights). Nights were particularly cold at the start of the month, reaching -6.8 °C on the 1st, the coldest September night on record for Canberra, with three consecutive nights falling below -4 °C. This is the latest such spell on record, with the previous record almost two weeks earlier in 22-24 August 1978.

Other phenomena

The prevailing wind direction at Canberra Airport was northwesterly, with 76% of 3pm winds between WNW and NNW, normal for September. There were four strong wind days reported at the airport, with a maximum wind gust of 80 km/hr on the 5th. Canberra Airport recorded an average of 8.0 hours of bright sunshine, slightly above the historical average of 7.7 hours, with two thunderstorms reported in the ACT on the 18th and 28th.

Further information

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Extremes in September 2012
Hottest day 23.7 °C at Tuggeranong (Isabella Plains) AWS on the 27th
Warmest days on average 18.0 °C at Canberra Airport
18.0 °C at Tuggeranong (Isabella Plains) AWS
Coolest days on average 8.6 °C at Mount Ginini AWS
Coldest day -1.5 °C at Mount Ginini AWS on the 7th
Coldest night -6.8 °C at Canberra Airport on the 1st
Coolest nights on average 0.0 °C at Mount Ginini AWS
Warmest nights on average 2.6 °C at Tuggeranong (Isabella Plains) AWS
Warmest night 10.9 °C at Tuggeranong (Isabella Plains) AWS on the 28th
Warmest on average overall 10.3 °C at Tuggeranong (Isabella Plains) AWS
Coolest on average overall 4.3 °C at Mount Ginini AWS
Wettest overall 83.4 mm at Mount Ginini AWS
Wettest day 48.8 mm at Mount Ginini AWS on the 29th
Highest wind gust 93 km/h at Mount Ginini AWS on the 28th

Summary statistics for September 2012
Maximum temperatures
for September
(°C)
Minimum temperatures
for September
(°C)
Rainfall
for September
(millimetres)
Mean for
September
2012
Diff
from
average
Highest for
September
2012
Mean for
September
2012
Diff
from
average
Lowest for
September
2012
Total for
September
2012
Average
for
September
Rank of
September
2012
Fraction of
September
average
Canberra Airport 18.0 +1.8 23.3 27th 1.6 -1.7 -6.8 1st 41.4 52.0 average 80%
Mount Ginini AWS 8.6   16.3 27th 0.0   -6.2 1st 83.4
Tuggeranong (Isabella Plains) AWS 18.0   23.7 27th 2.6   -5.5 1st 40.4

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 Tuesday 2 October 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.

Further information

Media
(03) 9669 4057
Enquiries