Australian Capital Territory in September 2017: dry weather reappears

The nation's capital was warm and dry for the start of spring. Canberra had its warmest September day on record on the 23rd, and its driest September since 1994. The clear skies continued to deliver below average overnight temperatures, including several late season cold records.

Dry conditions return

  • After average rainfall in August, September saw a return to dry conditions: only 13.4 mm fell at Canberra Airport this month making it the driest September since 1994 and the seventh-driest on record
  • Rain fell on six days at Canberra Airport, below the average of 10 days
  • The June to September rainfall total for Canberra is only 50 per cent of the average, the third-driest June to September period on record
  • Only one day recorded more than 5 mm of rain at Canberra Airport this month, compared to a September average of 3 days: only 20% of Septembers since 1939 have failed to receive a daily total above 10 mm

Warm spring days, but winter nights linger

  • Canberra's mean maximum temperature was almost 2 °C above the September average, although similar to recent years
  • The 23rd was the warmest September day on record across the Territory; Canberra Airport hit a top of 30.2 °C, more than 1 °C warmer than the previous record set on the 26th of September 1965 and the first time a temperature above 30 °C has been recorded in September
  • Ten days reached a maximum temperature above 20 °C, more than the September average of four days
  • Minimum temperatures were slightly below average at Canberra Airport, but not as cold as 2015
  • A total of 13 frost days (days with minimum temperatures 2 °C or below) were recorded at Canberra Airport, slightly above the average of 12 days, including some unusually cold minimum temperatures for the second half of September: the temperature dropped below -5 °C for two nights in a row on the 17th and 18th
  • The warm days and cool nights made for some large daily temperature ranges: the 18th was the first time since May 1957 that the capital recorded a day of more than 20 °C after a night colder than -5 °C

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Extremes in September 2017
Hottest day 30.2 °C at Canberra Airport on the 23rd
Warmest days on average 18.1 °C at Canberra Airport
Coolest days on average 7.4 °C at Mount Ginini AWS
Coldest day -2.2 °C at Mount Ginini AWS on the 5th
Coldest night -6.6 °C at Mount Ginini AWS on the 6th
Coolest nights on average -0.6 °C at Mount Ginini AWS
Warmest nights on average 3.4 °C at Tuggeranong (Isabella Plains) AWS
Warmest night 13.2 °C at Tuggeranong (Isabella Plains) AWS on the 24th
Warmest on average overall 10.6 °C at Tuggeranong (Isabella Plains) AWS
Coolest on average overall 3.4 °C at Mount Ginini AWS
Wettest overall 52.6 mm at Mount Ginini AWS
Driest overall 8.2 mm at Nicholls (Gungahlin Lakes)
Wettest day 15.0 mm at Mount Ginini AWS on the 6th
Strongest wind gust 102 km/h at Mount Ginini AWS on the 23rd


Record highest September temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Canberra Airport 30.2 on the 23rd 28.6* on the 26th in 1965 79 16.2
Tuggeranong (Isabella Plains) AWS 29.4 on the 23rd 26.4 on the 30th in 1998 22 17.6
* Present observations are taken at “Canberra Airport” (Bureau number 070351), which opened in late 2008. The previous record was set at Canberra Airport Comparison (070014), which ran from 1939 to 2010.



Record highest September daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Tuggeranong (Isabella Plains) AWS 13.2 on the 24th 12.9 on the 24th in 2003 22 3.8



Summary statistics for September 2017
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
September
2017
Diff
from
average
Highest for
September
2017
Mean for
September
2017
Diff
from
average
Lowest for
September
2017
Total for
September
2017
Average
for
September
Rank of
September
2017
Fraction of
September
average
Canberra Airport 18.1   30.2 23rd 2.7   -6.1 17th 13.4 50.0 low 27%
Mount Ginini AWS 7.4 -1.2 19.9 23rd -0.6 -0.9 -6.6 6th 52.6 90.5 average 58%
Tuggeranong (Isabella Plains) AWS 17.8 +0.2 29.4 23rd 3.4 -0.4 -5.0 17th 13.2 60.8 low 22%
Note: Observations for “Canberra Airport” are taken from the current site (Bureau number 070351), which opened in late 2008.
Comparisons are made against data from the previous site Canberra Airport Comparison (070014), which ran from 1939 to 2010.

Daily maximum temperatures for September 2017
123456789101112131415161718192021222324252627282930
Canberra Airport15.018.023.512.89.610.013.013.814.716.919.923.822.512.413.614.916.720.114.918.222.625.230.221.417.519.424.320.319.517.9
Mount Ginini AWS7.78.29.6-1.1-2.2-0.9-0.5-0.95.67.27.310.38.2-0.21.33.38.610.56.611.814.016.219.98.95.611.916.610.59.57.4
Tuggeranong (Isabella Plains) AWS15.118.121.412.09.310.813.613.714.416.619.623.321.312.314.214.916.520.014.617.523.224.829.420.016.819.423.820.318.917.6
Values are the maximum temperature, usually in the 24 hours from 9 am on the day indicated,
and typically occurred in the afternoon of that day.
Temperatures coloured according to their difference
from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C Grey outline marks highest
and lowest for the period

Daily minimum temperatures for September 2017
123456789101112131415161718192021222324252627282930
Canberra Airport-4.7-3.91.05.52.43.44.85.30.6-3.2-2.43.68.44.47.08.0-6.1-5.62.8-4.1-1.11.11.312.78.14.21.410.47.110.0
Mount Ginini AWS-2.7-0.12.7-2.3-5.9-6.6-4.8-2.3-4.5-2.3-0.92.25.1-5.2-4.1-0.5-5.51.4-2.3-3.04.05.59.32.8-0.6-2.62.34.5-0.1-1.0
Tuggeranong (Isabella Plains) AWS-3.3-3.20.87.52.54.05.95.5-0.5-2.5-2.35.011.75.47.49.1-5.0-4.23.1-2.4-0.22.71.013.29.71.61.610.97.610.3
Values are the minimum temperature, usually in the 24 hours to 9 am on the day indicated,
and typically occurred that morning.
Temperatures coloured according to their difference
from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C Grey outline marks highest
and lowest for the period

Daily rainfall for September 2017
123456789101112131415161718192021222324252627282930
Bruce (Australian Institute of Sport) - 0.2 1.8 - 1.4 1.2 - - - - - - - 1.4
Canberra (Australian National Botanic Ga - - 1.0 - 2.0 2.5 1.3 0.9 - - - - - - - 1.0 - - - - - - - -





Canberra Airport - - - - 1.6 2.8 0.6 - - - - - - - - 0.4 0.4 - - - - - - - - - - 7.6 - -
Ginninderra (Charnwood (ACT)) - - - - 2.2 2.8 0.8 1.0 - 0.2 - - - - - 0.2 0.2 - - - - - - - - - - - 0.2
Mount Ginini AWS - - 0.2 0.2 7.4 15.0 10.8 7.0 - 0.2 - - 0.6 - 1.2 3.6 1.2 - 2.0 - - - - - - 0.6 - 2.6 - -
Nicholls (Gungahlin Lakes) - - - - 3.4 3.4 1.4






















Sutton (Uba) - - - - 3.0 3.6 1.0 0.4 - - - - - - - 0.4 0.3












Torrens (Darke St) - - 0.2 - 3.0 3.8 0.8 0.8 - - - - - 0.4















Tuggeranong (Isabella Plains) AWS - - 0.2 - 4.2 3.6 - 0.6 - - - - - 0.2 - 0.2 - - - - - - - - - - - 4.2 - -
Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with → are part of a longer accumulation, which is shown on the final day.
Values over 100 mm have been rounded to the nearest whole millimetre.
Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
Rainfalls coloured
according to the amount
0 1.0 5.0 10.0 15.0 25.0 50.0 100 150 200 300 400 600 millimetres

Notes

The Monthly climate summary, generally published on the first working day of each month, lists the main features of the weather in Australian Capital Territory using the most timely and accurate information available on the date of publication; it will generally not be updated. More extensive discussion of significant weather events, along with later information and data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review.

In September 2017 this summary was broadened to include data from observing sites in or near the Australian Capital Territory “Greater Capital City Statistical Area” (GCCSA). The Australian Bureau of Statistics designed the GCCSAs to “include the population within the urban area of the city, as well as people who regularly socialise, shop or work within the city, and live in small towns and rural areas surrounding the city. It is important to note that GCCSAs do not define the built up edge of the city. They provide a stable definition for these cities and are designed for the output of a range of social and economic survey data.

This statement has been prepared based on information available at 11 am on Monday 2 October 2017. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

In some situations, some or all of the rainfall is in the form of hail or snow. In these cases the totals given are for the water equivalent: the depth of liquid water that results from melting any frozen precipitation. There can be significant 'undercatch' of snow in strong winds, meaning the true precipitation can be higher than that reported.

Averages for individual sites 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 10 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.

Where temperature area averages are mentioned, they are derived from the ACORN-SAT dataset.

Further information

Media
(03) 9669 4057
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