Monday, 3 January 2005

MONTHLY CLIMATE SUMMARY - ACT

December was wetter and warmer than normal in ACT

The ACT was wetter and warmer than normal in December 2004. There were more thunderstorms than average, and daytime and night-time temperatures were above average.

Rainfall: A total of 72.4 mm of rain was recorded at Canberra Airport over 10 rain days in December. The monthly average is 52.5 mm over seven days. Most of the rain fell between 5 and 14 December and was associated with thunderstorm activity. Dry conditions were experienced in the last two weeks of the month. There were nine thunderstorm days at the airport (average three) and one day of hail associated with a thunderstorm on 13 December. Hail and heavy rainfall were also recorded in the northern suburbs on the 7th. This is the greatest number of December thunderstorms since 1971 when 10 thunderstorm days were recorded. The heavy rain and thunderstorms were quite widespread. Most weather stations across the territory recorded well above-average rainfall. The highest total was 164.8 mm at Tidbinbilla. The lowest was 64.8 mm at the Botanic Gardens. The thunderstorms on 6, 7 and 13 December could be classified as severe thunderstorms due to the heavy rain and significant flash flooding that occurred across the ACT.

Temperature: The December mean daily maximum temperature of 26.6 degrees Celsius was above the average of 26.0°C. The mean daily minimum temperature of 12.0°C was also above the average of 11.2°C. There were five days when temperatures of 30°C or more were recorded, one day less than the average. There were no days of 35°C or more compared with the average of one day. There was one frost in December on the 29th (average none) and no fogs. The mean daily temperature of 19.3°C (the average of the daily maximum and minimum temperatures) was above the long-term figure of 18.6°C. The mean daily sunshine of 10.0 hours a day was also more than the average of 9.3 hr/day.

Other: The monthly wind run at two metres was 207 kilometres a day, less than the long-term average of 215 km/day. But there were four days of strong winds, double the long-term average of two days. Evaporation for December was 239.0 mm, just below the average of 250.8 mm due to the wetter and less windy conditions. The average daily air pressure of 1011.7 hectopascals was marginally greater than the average of 1011.3 hPa.

Summary for Canberra airport, December 2004

Mean maximum temperature: 26.6°C (av 26.0)
Highest maximum temperature: 34.8°C (19 December)
Lowest maximum temperature: 19.9°C (28 December)
Mean minimum temperature: 12.0°C (av 11.2)
Highest minimum temperature: 21.8 °C (1 December)
Lowest minimum temperature: 4.1 °C (29 December)
Lowest grass temperature: minus 0.9°C (29 December)
Total monthly rainfall: 72.4 mm (av 52.5)
Total monthly evaporation: 239.0 mm (av 250.8)
Mean daily sunshine: 10.0 hr/day (av 9.3)
Mean daily pressure: 1011.7 hPa (av 1011.3)
Mean daily wind run (at 2 metres): 207 km/day (av 215)

Ends

Further information:
Clem Davis, Canberra Meteorological Office, tel: (02) 6249 6269, e-mail: c.davis@bom.gov.au