Tuesday, 6 January 2009 - Monthly Climate Summary for Canberra rainfall extremes - Product code IDCKGC25x0

Canberra ends year with mild, wet December

Summary

  • Well above average rainfall, wettest December since 1999
  • Cool days, below average maximum temperatures
  • Mild nights, warmer than average minimum temperatures
  • Plentiful sunshine averaging 9.9 hours per day

An archive of previous monthly summaries for Canberra rainfall extremes is also available, as are summaries for other states and many other climate summaries and diagnostics.

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Rainfall

Canberra Airport recorded a total rainfall of 116.6 mm during December, which is well above the historical average1 of 53.4 mm, and the wettest December since 1999. The rain fell on 12 rain days (historic average 8 rain days). Almost half of the month's rainfall occurred on one day (the 13th) associated with a deep low pressure system over southern NSW with the remainder from thunderstorms during the second half of the month.

The wettest parts of the ACT were in central and southern suburbs with lower rainfall in the north and far west of the ACT. The highest total for December was 147.6 mm at Curtin (Deakin West) while the lowest was 92.2 mm at Cook in the northwest.

Temperatures

Generally mild days prevailed in Canberra during December. The mean maximum temperature at Canberra Airport was 25.3 °C, which is 0.8 °C below the historical average of 26.1 °C. There was a distinct lack of hot days in the city this month with only one day exceeding 30 °C. The last December that recorded only one hot day was back in 1992. Normally Canberra would expect 7 hot days during December. The wetter conditions and prevailing E-SE winds contributed to the milder daytime temperatures.

Night-time temperatures were slightly above average, with a mean minimum temperature of 11.9 °C at Canberra Airport, which is 0.6 °C above the historic average. At Canberra Airport, minimum temperatures ranged from a low of 5.6 °C on the 2nd to a high of 16.5 °C on the 7th. The lowest temperature in the ACT during December was -1.0 °C at Mount Ginini AWS (in the mountains SW of Canberra, elev 1760 metres) on the 20th.

Wind

Although W-NW winds prevailed during December, which is typical for most of the year in Canberra, there was a greater incidence of E-SE winds this month than what normally would be expected in December. There were 3 strong wind days* during the month (average for December). The strongest winds were on the 13th associated with a deep low pressure system over southern NSW with gusts of 83 km/h at Canberra Airport.

Other phenomena

Canberra experienced a generally sunny month with an average of 9.9 hours of sunshine per day, compared to the historic December average of 9.4 hours per day. There were only 5 cloudy or overcast days compared to the normal 10 cloudy days for December. Canberra Airport recorded 4 thunderstorms during the month, on the 17th, 18th, 23rd and 27th. The most severe was on the 27th with heavy showers recorded in some Canberra suburbs causing local flash flooding in the Deakin-Curtin area. The highest fall was 56mm at Curtin (Deakin West).

Further information

NSW Climate Services Centre
NSW Regional Office
Bureau of Meteorology
Phone (02) 9296 1555
Email reqnsw@bom.gov.au

* string wind day defined as average wind speed of 40 km/hr or more over a 10 minute period.

Extremes

Hottest day
Highest temperature		 30.9 °C at Tuggeranong AWS on the 26th
Warmest days on average
Highest mean daily maximum temperature		 25.3 °C at Canberra Airport
Coolest days on average
Lowest mean daily maximum temperature		 24.9 °C at Tuggeranongi AWS
15.6 °C at Mount Ginini AWS
Coldest day
Lowest daily maximum temperature		19.5 °C at Canberra Airport on the 14th
8.0 °C at Mount Ginini on the 14th
Coldest night
Lowest temperature

5.6 °C at Canberra Airport on the 2nd
-1.0 °C at Mount Ginini AWS on the 20th

Coolest nights on average
Lowest mean daily minimum temperature

11.9 °C at Canberra Airport
5.8 °C at Mount Ginini AWS
Warmest nights on average
Highest mean daily minimum temperature		 12.2 °C at Tuggeranong AWS
Warmest night
Highest daily minimum temperature		 16.5 °C at Canberra Airport on the 7th
Wettest overall
Highest total rainfall		 147.6 mm at Curtin (Deakin West)
Driest overall
Lowest total rainfall		 92.2 mm at Cook (Springvale Drive)
Wettest day
Highest daily rainfall		 67.2 mm at Curtin (Deakin West) on the 13th
Highest wind gust
 83 km/h at Canberra Airport on the 13th

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Records

Nil

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Summaries

This table is very wide and may not fit if printed.

Summary statistics for December 2008
Maximum temperatures
for December
(°C)		 Minimum temperatures
for December
(°C)		 Rainfall
for December
(millimetres)
Mean for
December
2008		 Diff
from
average		 Highest for
December
2008		 Mean for
December
2008		 Diff
from
average		 Lowest for
December
2008		 Total for
December
2008		 Average
for
December		 Rank of
December
2008		 Fraction of
December
average
Canberra Airport 25.3 -0.8 30.8 26th 11.9 +0.6 5.6 2nd 116.6 53.4 very high 218%
Mount Ginini AWS 15.6   22.0 26th 5.8   -1.0 20th 99.8
Tuggeranong 24.9 -2.3 30.9 26th 12.2 +0.2 5.7 2nd 105.2 51.1 high 206%

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Notes

This statement has been prepared based on information available at 10 am on Tuesday 6 January 2009. 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 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.

Further information

NSW Climate Services Centre
NSW Regional Office
Bureau of Meteorology
Phone (02) 9296 1555
Email reqnsw@bom.gov.au