Thursday, 5 January 2006
Annual Climate Summary – ACT
Warm days, more rain and less fog for the ACT in 2005
While both rainfall and temperature figures were higher than average across the territory in 2005, the unusually warm daytime temperatures in most months were the most significant weather feature of the year. Compared to the averages, there was one less thunderstorm day, more strong wind days and considerably less fog.
Rainfall: Canberra airport recorded 648.6 millimetres of rain for the year. This figure is just above the average of 625.2 mm. The driest period occurred throughout April and May with 6.8mm and 0.8mm of rain respectively. The wettest month of the year was September with 100.6 mm of rain, which is nearly twice the monthly average. Most other months recorded rainfall that was either close to, or above, average. The wettest 24-hour total to 9am occurred on 9 July with 48mm followed by 43.8 mm on 8 November. The latter was associated with a thunderstorm that also produced some large hail. There were two other occasions where 30 mm or more of rain was recorded (12 June with 40mm and 21 January with 32mm) while there were eight occasions of between 20 and 30 mm falling in the 24-hour period to 9 am.
Thunderstorms: There were 109 actual rain days for the year (four days more than the average), with 22 days of thunderstorms (one less than the average). Three of the thunderstorms observed were severe: on 24 October and 26 November due to large hail and on 2 December due to damaging winds. Thunderstorm activity was highest during February and November, with both months recording five days compared to the average of three days each. In total, eight hail days were recorded at the airport during the year with large hail falling in the northern suburbs during October and November. There was no record of snow falling at the airport during the year.
Temperature: The overall mean daily temperature for 2005 was 14.2 degrees Celcius, well above the long-term average of 13.0 °C and the highest on record. The mean annual daytime maximum temperature of 21.0 °C was above the average of 19.6 °C while the mean annual nighttime temperature of 7.2 °C was also above the average of 6.5 °C.
This is also the ninth consecutive year that the mean daily maximum and minimum temperatures for Canberra have either been average or above average. The warmest month was January (average daily temperature 21.5 °C) and the coldest was July (average daily temperature 7.1 °C).
Max temps: The mean daily maximum temperatures were above average for all months, except March where it was 0.2 degree below. The highest average daily maximum temperature by month was 29.9 °C in January. The temperature reached 30.0 °C or more on 48 days during 2005, compared to the average of 30 days. The highest number of such days was recorded in January with 16 days compared to the average of 10 days. There were also 12 days where a temperature of 35.0 °C or more was recorded, more than twice as many as the average of five days. Four of these days occurred in January, two in February, two in November and four in December. The hottest day of the year was on 14 January with 39.4°C.
Min temps: Mean daily minimum temperatures were below average for March, May and August but above average for all other months. The lowest average daily maximum by month was 12.7 °C in July and the coldest day of the year was 6.9 °C on 11 August.
There were 82 frosts recorded, 17 less than the yearly average. Fifty of these frosts occurred in winter (seven less than average for the season), 12 in spring (nine less than average) and 20 in autumn (two more than average). The first frost of the year was recorded on 6 March (the median date for the first frost is 9 April) while the last frost was recorded on 12 October (the median date for last frost is 16 November). The coldest morning of the year was minus 4.7 °C on 2 June.
Fogs: There were only 18 fogs for the year, a new record low at less than half the average of 44 fogs. The previous record was set in 2004 with 20 fogs. No fogs were recorded in January, February, November or December where the monthly averages are one for each month. All other months recorded either an average or below average number of fogs. The foggiest month was July with five fogs, two below the average.
Wind: Overall 2005 was a windy year. The mean daily wind run for the year was 191.3 kilometres per day, exceeding the long-term average of 183.9 km/day. The windiest month was December with 255 km/day, while April was the calmest at 137 km/day. There were 25 strong wind days recorded, which met the average. There were also five occasions where gales were recorded in the ACT where the average is one day/year. The highest wind gust for the year was 100 km/h on 2 December.
Sunshine: Canberra had an average of 8.2 hours of sunshine per day for the year, well above the mean of 7.6 hours/day. February, June, September, October and November all recorded below average sunshine while December set a record high at 11.4 hours for the month. The evaporation of 1753.6 mm for the year was considerably more than the average of 1686.6 mm.
Pressure: The average daily pressure of 1017.3 hectopascals was very close to the average of 1016.7 hPa. April recorded the highest mean daily pressure of 1023.3 hPa while December recorded the lowest with 1008.7 hPa. One of the highest pressures ever recorded at the airport occurred on 20 June at 1041.9 hPa.
Summary for Canberra airport, 2005
Mean maximum temperature: 21.0°C (av 19.6°C)
Highest maximum temperature: 39.4 °C (on 14 January)
Lowest maximum temperature: 6.9 °C (on 11 August)
Mean minimum temperature: 7.2 °C (av 6.5°C)
Highest minimum temperature: 19.2 °C (on 26 February)
Lowest minimum temperature: minus 4.7 °C (on 2 June)
Mean daily temperature: 14.2 °C (av 13.0 °C)
Lowest grass temperature: minus 8.9 °C (on 2 June)
Annual rainfall: 648.6 mm (av 625.2 mm)
Annual evaporation: 1753.6 mm (av 1686.6 mm)
Mean daily sunshine: 8.2 hours/day (av 7.6 h/day)
Mean daily pressure: 1017.3 hPa (1016.7 hPa)
Mean daily wind run (at 2 metres): 191.3 km/day (av 183.9 km/day)
