Tuesday, 1 March 2005

SEASONAL CLIMATE SUMMARY - ACT

Thunderstorms highlight a warm and windy summer in the ACT

Thunderstorms were more frequent than normal during summer 2004-05 in the ACT. The storms produced some high rainfall totals - including a well above-average total at Canberra airport - but overall rainfall was about average across the territory. Temperatures were generally above average.

Rainfall: A total of 203.2 millimetres of rain fell over 22 days at Canberra airport during summer. The average is 168.1 mm over 21 days. While rainfall totals were well above average in December and February, the January reading was just below average. There was 72.4 mm of rain over 10 days in December, 57.2 mm over four days in January, and 73.6 mm over eight days in February. The heaviest 24-hour total to 9 am was 32.0 mm on 21 January. There were 16 thunderstorm days for the season (average 11) – nine days in December, two in January and five in February. Hail associated with the thunderstorms was recorded at the airport on three occasions, once in each month. There were five occasions (6, 7 and 13 December, and 4 and 20 January) when thunderstorm activity was reported as severe. Normally the ACT records only one or two severe thunderstorms a year, usually in the spring-to-autumn period. Heavy rainfall and thunderstorms were also reported on 2 and 12 February, but the storms did not reach the severe level. The local nature of the thunderstorms resulted in variable rainfall totals across the ACT, especially in February.

Temperature: The mean daily maximum temperature for summer in the ACT was 27.6 degrees Celsius, higher than the long-term average of 26.9 degrees. Maximum temperatures were above average in December and January and just below average in February. The temperature reached 30.0 degrees or more on 31 occasions over the summer (average 25) and reached 35.0 degrees or more on six occasions (average four). The highest temperature for summer was 39.4 degrees on 14 January. The coldest day was 15.3 degrees on 3 February.

The mean daily minimum temperature for summer was 13.1 degrees, well above the average of 12.4. The mean minimum was above average in all months. There was one frost for the season (average one) on 29 December.

The average daily temperature for summer was 20.3 degrees, well above the long-term mean of 19.6.

Sunshine: The average daily sunshine of 9.6 hours a day was slightly more than the long-term average of 9.2. Sunshine hours was more than average in December and January but less than average in February.

Wind: The average daily wind run for summer was 202.8 kilometres a day, further than the long-term average of 195.9 km/day. There were eight strong wind days (average five), of which four were in December, two were in January and two were in February. Gales were recorded on two days - 4 January and 3 February - compared with the average of none.

Other: Total summer evaporation of 697 mm was slightly less than the long-term average of 703.3. There were no fogs (average three), while the mean daily pressure of 1011.6 hectopascals was less than the average of 1012.5.

Summary for Canberra airport, summer 2004-05

Mean maximum temperature: 27.6°C (av 26.9°C)
Highest maximum temperature: 39.4°C (14 January)
Lowest maximum temperature: 15.3°C (3 February)
Mean minimum temperature: 13.1°C (av 12.4°C)
Highest minimum temperature: 21.8°C (1 December)
Lowest minimum temperature: 4.1°C (29 December)
Mean daily temperature: 20.4°C (av 19.6°C)
Lowest grass temperature: minus 0.9°C (29 December)
Total summer rainfall: 203.2 mm (av 168.1 mm)
Total summer evaporation: 697.0 mm (av 703.3 mm)
Mean daily sunshine: 9.6 hr/day (av 9.3 hr/day)
Mean daily pressure: 1011.6 hPa (av 1012.5 hPa)
Mean daily windrun (at two metres): 202.8 km/day (av 195.9 km/day)

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

Ends