Wednesday, 1 July 2009 - Monthly Climate Summary for ACT Monthly Summary - Product code IDCKGC25R0

ACT Monthly Summary in June 2009
Mild and cloudy conditions for the ACT

Summary

  • Close to average rainfall
  • 4th warmest June on record for territory wide minimum temperatures
  • Above average maximum temperatures
  • Below average sunshine hours and above average cloud cover

An archive of previous monthly summaries for ACT Monthly Summary is also available, as are summaries for other states and many other climate summaries and diagnostics.

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Rainfall

The ACT received close to average rainfall during June, with some spatial variation across the territory. Canberra airport recorded a total of 36.8 mm, which is slightly below the average of 40.8 mm. Tidbinbilla Nature Reserve, to the south west of Canberra recorded 49 mm of rain, only equating to 74% of its average June rainfall of 66.2 mm. Canberra Airport reported 17 raindays in June, well above the average of 9 days.

The majority of the month's rainfall fell in two main events. The first occured between the 3rd and 8th of June, when a trough in the Tasman combined with a cold front, triggering further rainfall. The second event occured around the 21st of June and was largely caused by a high pressure system in the Tasman as well as an offshore trough.

Temperature

Maximum temperatures were slightly above average during June in the ACT. Canberra Airport recorded an average maximum temperature of 12.7°C, which was 0.5°C above the average maximum of 12.2°C.

Minimum temperatures were well above average across the ACT. The average minimum temperature at Canberra Airport was 3.3°C which is 2.3°C above the historic May average, making it the 4th warmest June for minimum temperatures out of 69 years of record. Canberra Airport reported frost on 12 days during June, less than the average of 18 days.

Temperature extremes in the ACT ranged from a high of 16.8°C at Canberra Airport on the 30th, to an overnight low of −8.5°C at Mount Ginini on the 11th. This minimum temperature occured due to a low pressure system in the Tasman Sea, which brought cool southerly wind into the ACT.

Wind

NW winds prevailed over the ACT during June for 37% of the time during the afternoons, which is only 2% more than average. The wind speed was moderate during most of the month, with the strongest gust of 107 km/h recorded at Mount Ginini AWS (elev 1760 metres) and at Canberra Airport (72km/h) on the 30th. This was caused by the leading edge of a strong cold front moving into western NSW.

Other phenomena

Conditions were cloudy during June, with an average morning cloud cover of 6.2 oktas reported, well above the long-term average of 4.6 oktas. Cloud cover was also above average for the afternoon, reporting an average of 5.3 oktas compared to the long-term average of 4.5 oktas. Average daily sunshine hours were below average, reporting a June daily average of 4.2 hours of sunshine, compared to the long-term average of 5.2 hours. One weak thunderstorm was recorded over the ACT on the 5th. At Canberra Airport, fog was observed on 10 days during June, slightly above the average of 7.7 days.

Further information

Claire Davis
Climate Officer
NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email climate.nsw@bom.gov.au

Extremes

Hottest day
Highest temperature		 16.8°C at Canberra Airport on the 30th
Warmest days on average
Highest mean daily maximum temperature		 12.7°C at Canberra Airport
Coolest days on average
Lowest mean daily maximum temperature		 3.3°C at Mount Ginini AWS
12.0°C at Tidbinbilla Nature Reserve
Coldest day
Lowest daily maximum temperature		 −2.2°C at Mount Ginini AWS on the 9th
2.6°C at Tuggeranong (Isabella Plains) AWS on the 12th
Coldest night
Lowest temperature		 −8.5°C at Mount Ginini AWS on the 11th
−6.0°C at Tuggeranong (Isabella Plains) AWS on the 11th
−5.8°C at Canberra Airport on the 11th
Coolest nights on average
Lowest mean daily minimum temperature		 −1.2°C at Mount Ginini AWS
2.3°C at Tidbinbilla Nature Reserve
Warmest nights on average
Highest mean daily minimum temperature		 3.4°C at Tuggeranong (Isabella Plains) AWS
Warmest night
Highest daily minimum temperature		 10.2°C at Tuggeranong (Isabella Plains) AWS on the 5th
Wettest overall
Highest total rainfall		 99.8 mm at Mount Ginini AWS
49.0 mm at Tidbinbilla Nature Reserve
Driest overall
Lowest total rainfall		 28.4 mm at Tuggeranong (Isabella Plains) AWS
Wettest day
Highest daily rainfall		 18.2 mm at Mount Ginini AWS on the 4th
Highest wind gust
 107 km/h at Mount Ginini AWS on the 30th

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Summaries

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

Summary statistics for June 2009
Maximum temperatures
for June
(°C)		 Minimum temperatures
for June
(°C)		 Rainfall
for June
(millimetres)
Mean for
June
2009		 Diff
from
average		 Highest for
June
2009		 Mean for
June
2009		 Diff
from
average		 Lowest for
June
2009		 Total for
June
2009		 Average
for
June		 Rank of
June
2009		 Fraction of
June
average
Canberra Airport 12.7 +0.5 16.8 30th 3.3 +2.3 −5.8 11th 36.8 40.7 average 90%
Mount Ginini AWS 3.3   8.1 22nd −1.2   −8.5 11th 99.8
Tidbinbilla Nature Reserve 12.0 +0.3 14.5 5th 2.3 +1.0 −4.0 11th 49.0 66.2 average 74%
Tuggeranong 12.4   16.3 30th 3.4   −6.0 11th 28.4

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Notes

This statement has been prepared based on information available at 11 am on Wednesday 1 July 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 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

Claire Davis
Climate Officer
NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email climate.nsw@bom.gov.au