FYI: Monthly Climate Summary for Canberra - May 2009 [SEC=UNCLASSIFIED]

With climate being such an important
factor in our bird population, the following is provided for the information
of subscribers (and as an addition to the annual summary provided in the
Annual Bird Report): 

http://www.bom.gov.au/climate/current/month/act/summary.shtml

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

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.********************************************************************** IMPORTANT: This e-mail is intended for the use of the addressee and may contain information that is confidential, commercially valuable or subject to legal or parliamentary privilege. If you are not the intended recipient you are notified that any review, re-transmission, disclosure, use or dissemination of this communication is strictly prohibited by several Commonwealth Acts of Parliament. If you have received this communication in error please notify the sender immediately and delete all copies of this transmission together with any attachments. **********************************************************************