Monday, 2 June 2008 - Monthly Climate Summary for Canberra rainfall extremes - Product code IDCKGC1xx0

Mild, dry and sunny in Canberra during May

Details

Below average rainfall
Above average maximum temperature
Below average minimum temperatures
Frequent frosts and fogs
Sunny month - 2nd sunniest May on record

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Rainfall

Canberra Airport recorded a total rainfall of only 12.6 mm during May, which is well below the historical average¹ of 45.1 mm. This is now the 8th consecutive May with below average rainfall in Canberra and is a continuation of dry conditions experienced in Canberra at this time of year since the mid 1990's. There were only 6 rain days during the month, compared to the historic average of 8 days. Monthly totals around the ACT ranged from a high of 25 mm at Mount Ginini AWS to a low of 8.8 mm at Tharwa.

Persistent high pressure systems prevailed over the ACT during May causing a stable weather pattern and below average rainfall over the whole ACT region. The only rain bearing systems during May was the passage of a cold front on the 17th (also bringing snow to the Brindabella Ranges), and a low pressure trough on the 26th and 27th.

Temperatures

Above average maximum temperatures prevailed over the ACT during May. The mean maximum temperature for Canberra Airport was 17.2 ºC, which is well above the historical average²of 15.3 °C. This is now the 8th consecutive May with above average maximum temperatures in Canberra. Plentiful sunshine and a prevailing NW wind contributed towards the mild days. The highest temperature in the ACT was 21.1 °C at Tuggeranong AWS on the 10th.

The average minimum temperature at Canberra Airport was 2.5 ºC, or 0.8 °C below the historic average minimum. However, at the more sheltered location of Tuggeranong the average minimum was 0.9 °C or nearly 2 °C below the historical average and the lowest since 1996. A total of 19 frosts (minimum temperature below 2 °C) were recorded at Tuggeranong for the month, the highest at that site since records commenced in 1996. The historical average is 14 days below 2 °C. Persistent high pressure systems with mostly clear, calm nights contributed towards the frosty conditions. The lowest temperature in the ACT was -3.5 °C at Tuggeranong on the 19th, following a cold front.

Wind

The prevailing direction over the ACT during the afternoons was W-NW observed around 70% of the time. This is significantly higher than the normal frequency from this direction during May. The highest wind gust was 52 km/hr at Canberra Airport on the 17th and 19th associated with the passage of cold fronts.

Other phenomena

Canberra Airport recorded 12 fogs during May, the highest number for May since 1985 (the historic May average is 7 fogs). Canberra averaged 7.5 hours of sunshine per day, the 2nd sunniest May on record and well above above the historical average of 5.9 hours. No thunderstorm activity or strong winds were reported at Canberra Airport during May.

Further information

Mike De Salis
Climate Information Officer
NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email reqnsw@bom.gov.au

Extremes for the ACT

Hottest day Highest temperature	21.1 °C at Tuggeranong AWS on the 10th
Warmest days on average Highest mean daily maximum temperature	17.2 °C at Canberra Airport and at Tuggeranong AWS
Coolest days on average Lowest mean daily maximum temperature	17.2 °C at Canberra Airport and Tuggeranong AWS and 7.8 °C Mount Ginini AWS (elevation 1760m)
Coldest day Lowest daily maximum temperature	11.9 °C at Tuggeranong AWS on 17th and 0.4 °C at Mount Ginini AWS on the 18th
Coldest night Lowest temperature	-3.5 °C at Tuggeranong AWS on the 19th
Coolest nights on average Lowest mean daily minimum temperature	0.9 °C at Tuggeranong AWS
Warmest nights on average Highest mean daily minimum temperature	2.5 °C at Canberra Airport
Warmest night Highest daily minimum temperature	9.4 °C at Canberra Airport on the 12th
Wettest overall Highest total rainfall	25.0 mm at Mount Ginini AWS and 24.8 mm at Canberra Botanic Gardens
Driest overall Lowest total rainfall	8.8 mm at Tharwa
Wettest day Highest daily rainfall	20.6 mm at Tuggeranong Creek on the 10th
Highest wind gust	52 km/h at Canberra Airport on the 17th and 19th

AWS = Automatic Weather Station

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Summaries for the ACT

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

Summary statistics for May 2008
	Maximum temperatures for May (°C)				Minimum temperatures for May (°C)				Rainfall for May (millimetres)
	Mean for May 2008	Diff from normal	Highest for May 2008		Mean for May 2008	Diff from normal	Lowest for May 2008		Total for May 2008	Normal for May	Rank of May 2008	Fraction of May normal
Canberra Airport	17.2	+1.9	21.0	9th	2.5	-0.8	-2.7	19th	12.6	45.1	low	28%
Tuggeranong**	17.2	+0.6	21.1	10th	0.9	-1.8	-3.5	19th	11.0	21.9	normal	50%
Mount Ginini*	7.8		14.0	9th	1.1		-3.2	18th	25.0

* new station, no historic averages available

** short record 1996 - 2007 only

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Notes

This statement has been prepared based on information available at 11am on Monday 2 June 2008. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Normals 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 "normal" 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, normal in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of normal shows how much rain has fallen this time as a percentage of the long-term mean.

Further information

NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555