Monday, 1 June 2009 - Monthly Climate Summary for Canberra rainfall extremes - Product code IDCKGC25x0

Canberra has 6th driest May on record

  • Well below average rainfall, 6th driest May on record
  • Mild days, well above average maximum temperatures
  • 9th consecutive May with above average maximum temperatures
  • Mild nights, above average minimum temperatures
  • Above average sunshine hours

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.

Rainfall

Following welcome rainfall over the ACT during April, very dry conditions once again returned to the region during May. Canberra Airport recorded its 6th driest May on record with a total of only 2.4 mm. This compares to the historic average1 of 44.1 mm. It is the lowest May total since 0.8 mm in May 2005 and zero rainfall in May 1982. There were 10 rain days at Canberra Airport during the month compared to the historic average of 7 rain days.

Dry conditions extended throughout the ACT with totals of only 5.0 mm at Tuggeranong and 29 mm at Mount Ginini (highest in ACT). The lowest total was 1.4 mm at Kingston. The failure of rain bearing cold fronts and westerly winds to penetrate central and eastern parts of NSW contributed toward the dry conditions during May. A weak southwest change on the 16th was the only system to affect the ACT producing some light showers, however, most recordings were generally less than 5 mm.

Temperatures

Days were very mild in the ACT during May with well above average maximum temperatures. Canberra Airport recorded an average maximum temperature of 16.5°C, which is 0.9°C above the historical average of 15.6°C. It ranks as the 15th warmest May out of 70 years of record. It is also the 9th consecutive year with above average maximum temperatures in May. Numerous clear, sunny days, especially in the first half of May, and the lack of any significant cool changes, contributed towards the mild daytime temperatures.

Overnight temperatures were also mild. The average minimum temperature at Canberra Airport was 4.2°C which is 1.1°C above the historic May average. There were less frosts than normal this May with a total of only 10 frosts (minimum temperature less than 2°C). The historical average number of frosts is 14.

Temperature extremes in the ACT ranged from a high of 19.8°C at Canberra Airport on the 9th to an overnight low of −1.1°C at Tuggeranong AWS on the 17th and −2.3°C at Mount Ginini AWS on the 29th. Both low minimum temperatures occurred following a weak surge of cold air from the south.

Wind

S-SE winds prevailed over the ACT during May for 54% of the time during the mornings which is three times the normal frequency from this direction. There were several days of strong winds over the higher parts of the ACT ranges during May with the strongest gust of 94 km/h recorded at Mount Ginini AWS (elev 1760 metres) on the 16th. In the Canberra metropolitan area, the strongest was 67 km/h at Canberra Airport on the 15th.

Other phenomena

Numerous clear, sunny days prevailed in the ACT during May, especially during the first half of the month. The amount of sunshine in Canberra during May averaged 6.4 hours per day, compared to the historical average of 6.0 hours per day. Although sunshine was above average, it was the lowest amount of sunshine in May for six years. No thunderstorms were recorded in Canberra during the month. Normally one storm can be expected on average. There were 9 days during May when fog was either observed at the airport or observed in patches in the immediate vicinity. On the 1st, visibility at the airport was reduced to 300 metres in fog.

Further information

Mike De Salis
Climate Officer
NSW Climate Services Centre
NSW Regional Office
Bureau of Meteorology
Phone (02) 9296 1555
Email climate.nsw@bom.gov.au

Extremes for the ACT

Hottest day
Highest temperature
19.8°C at Canberra Airport on the 9th
Warmest days on average
Highest mean daily maximum temperature
16.5°C at Canberra Airport
Coolest days on average
Lowest mean daily maximum temperature
16.4°C at Tuggeranong AWS
7.3°C at Mount Ginini AWS
Coldest day
Lowest daily maximum temperature
12.9°C at Tuggeranong and Canberra Airport on the 29th
2.3°C at Mount Ginini AWS on the 14th
Coldest night
Lowest temperature

−1.1°C at Tuggeranong AWS on the 17th
−2.3°C at Mount Ginini AWS on the 29th

Coolest nights on average
Lowest mean daily minimum temperature
1.0°C at Mount Ginini AWS
4.2°C at Canberra Airport
Warmest nights on average
Highest mean daily minimum temperature
4.3°C at Tuggeranong AWS
Warmest night
Highest daily minimum temperature
10.7°C at Tuggeranong AWS on the 15th
Wettest overall
Highest total rainfall
29.0 mm at Mount Ginini AWS
6.4 mm at Tharwa General Store
Driest overall
Lowest total rainfall
1.4 mm at Kingston (Boat Harbour)
Wettest day
Highest daily rainfall
17.8 mm at Mount Ginini AWS on the 16th
4.0 mm at Tharwa General Store on the 16th
Highest wind gust
94 km/h at Mount Ginini AWS on the 16th
67 km/h at Canberra Airport on the 15th

Records

Nil recorded


Summaries for the ACT

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

Summary statistics for May 2009
Maximum temperatures
for May
(°C)
Minimum temperatures
for May
(°C)
Rainfall
for May
(millimetres)
Mean for
May
2009
Diff
from
average
Highest for
May
2009
Mean for
May
2009
Diff
from
average
Lowest for
May
2009
Total for
May
2009
Average
for
May
Rank of
May
2009
Fraction of
May
average
Canberra Airport 16.5 +0.9 19.8 9th 4.2 +1.1 −0.5 7th 2.4 44.1 very low 5%
Mount Ginini AWS* 7.3   12.4 9th 1.0   −2.3 29th 29.0
Tuggeranong 16.4 −0.3 19.7 9th 4.3 +1.7 −1.1 17th 5.0 19.9 low 25%

* new station, no climatic averages available


Notes

This statement has been prepared based on information available at 11 am on Monday 1 June 2009. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

1 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.