Thursday, 2 June 2005

SEASONAL CLIMATE SUMMARY - ACT

Record warm autumn for a dry ACT

A record high average daytime temperature for autumn was set in the ACT this year, while rainfall was about one-third of average. The warm, dry conditions were due to the presence of a persistent sub-tropical high pressure belt across the region.

Temperature: The ACT’s average daily maximum temperature for autumn this year was a record 22.4 degrees Celsius, well above the long-term average of 19.9 degrees. The previous record of 22.1 degrees was set in the autumn of 1980. In March, the average maximum temperature was just 0.1 degrees below average, but all-time highs were set in April and May this year.

The average daily minimum temperature for autumn of 6.7 degrees was just below the long-term average of 7.0 degrees. Minimum temperatures were below average in March and May but well above average in April.

The overall average daily temperature for autumn was 14.6 degrees, a little more than one degree higher than the long-term average of 13.5 degrees.

Rainfall: Only 47.8 millimetres of rain was recorded over 11 days at Canberra Airport in autumn. The long-term average is 146.5 mm over 22 days. Last year, 13.4 mm of rain was recorded over six days - the lowest autumn total on record. The second driest autumn was in 1965 when 23.8 mm of rain fell. The second lowest number of rain days is nine, recorded in 1967. Thunderstorm activity was recorded on only one autumn day this year - 21 March - compared with the average of four days. There were no thunder days in either April or May.

Other: The average daily sunshine for autumn was 8.3 hours a day, well above the average of 6.9 hr/day. All months recorded above-average sunshine.

The first frost of the year occurred on 6 March compared with the median date of 8 April. There were 20 frosts in autumn, two more than average. May had 15 frosts compared with the average of 13, though many were very light. April had four frosts compared with the average of five.

Wind run in autumn was about average. The average daily wind run was 155.3 kilometres a day compared with the average of 155.2 km/day. There were three days of strong winds – in March and April - compared with the average of four days.

There were only six fogs for the season, much fewer than the average of 14. There were no fogs in March (average of two), four in April (average of four) and two in May (average of eight).

Autumn evaporation was 497.4 mm, much more than the average of 346.8 mm. The average daily pressure was 1021.2 hectopascals, about 2 hPa above average.

Summary for Canberra airport, autumn 2005

Mean maximum temperature: 22.4°C (av 19.9°C)
Highest maximum temperature: 34.1°C (15 March)
Lowest maximum temperature: 13.2°C (28 May)
Mean minimum temperature: 6.7°C (av 7.0°C)
Highest minimum temperature: 17.4°C (2 March)
Lowest minimum temperature: minus 3.7°C (21 May)
Mean daily temperature: 14.6°C (av 13.5°C)
Lowest grass temperature: minus 5.8°C (30 April)
Total rainfall: 47.8 mm (av 146.5 mm)
Total evaporation: 497.4 mm (av 346.8 mm)
Mean daily sunshine: 8.3 hr/day (av 6.9 hr/day)
Mean daily pressure: 1021.2 hPa (av 1019.4 hPa)
Mean daily wind run (at 2 metres): 155.3 km/day (av 155.2 km/day)

Further information:
Ken Batt, Canberra Meteorological Office, tel: (02) 6249 6269, e-mail: K.Batt@bom.gov.au

Ends