1 March 2006

CANBERRA MONTHLY AND SEASONAL CLIMATE SUMMARY - NSW REGIONAL OFFICE

ACT experiences hottest summer on record

Summer 2005/06 Main points:
Warmest summer on record
Equal highest mean daily maximum temperature on record
2nd highest mean daily minimum temperature on record
Many hot days. 44 days above 30ºC (av 25 days) and 14 days above 35ºC (av 5 days)
Below average rainfall

February 2006 Main Points:
4th warmest February on record
4th highest mean daily maximum temperature
Many hot days. 16 days above 30ºC (av 8 days) and 4 days above 35ºC (av 1 day)
Below average rainfall

Summer 2005/06

Temperatures:
ACT residents experienced their warmest summer since records commenced in 1939. Overall, the mean daily temperature (average of daily maximum and minimum temperatures) was 22.2 degrees, which far exceeded the seasonal average of 19.8 degrees¹(the previous record was 21.9 degrees in 1990/1991). All summer months recorded above average mean daily temperatures.

The mean daily maximum temperature of 29.9 degrees was the equal highest on record, (equal with the summer of 1990/1991), and is 2.9 degrees above the seasonal average of 27.0 degrees. In addition, the number of warm days (temperatures greater than 30.0 degrees) that occurred during summer was 44 days, which was well above the average of 25. The number of hot days (temperatures greater than 35.0 degrees) that occurred was 14 days, in comparison to the season average of 5 days. The highest maximum temperature recorded during summer was 39.9 degrees Celsius on 1 January. The coldest maximum temperature was 17.1 degrees on 3 December.

The mean daily minimum temperature of 14.5 degrees was 1.1 degrees above the average of 12.5 degrees and was the second highest summer mean daily minimum temperature ever recorded, behind the summer of 1980/1981 (14.8 degrees). The mean daily minimum temperatures were above average for each month of summer. The coolest temperature recorded was 6.2 degrees on 10 February. There were no fogs (average 2) or frosts (average zero) reported during summer

Rainfall:
Canberra Airport recorded 125.0mm of rain, falling over 13 of the 90 days of summer, which was below the average of 168.0mm² of rain over 22 days. January was the only month to exceed the long term average, with 79.0mm compared with the mean of 60.3mm. December was particularly dry, with only 19.8mm reported over two days in comparison to the average of 52.3mm over 8 days. The heaviest 24 hour total to 9am was 34.8mm on 17 January.

Thunderstorms were reported on 13 days through summer, compared to the seasonal average of 11. This included three in December, eight in January and two in February. A severe thunderstorm was reported on 2 December, which brought heavy rain and strong winds. Winds brought down hundreds of trees in south Canberra, especially in the Griffith/Fyshwick areas.  Buildings were unroofed, and a possible tornado was reported. A thunderstorm on 16 January produced heavy rain and flash flooding in the Canberra area. There were no reports of hail during the summer.

Sunshine, Wind, Evaporation and Pressure:
The average daily sunshine of 10.3hr/day was above the seasonal average of 9.2hr/day. December and February recorded above average hours, while January recorded less sunshine hours than average.

The average daily wind run for summer was 215.3km, which was above the long term average on 197.9km

The total summer evaporation of 814mm was above the seasonal average of 708mm.

The mean daily pressure of 1011.7hPa was below the long term mean of 1012.5hPa

February 2006

Temperatures:
The mean daily maximum temperature of 30.5 degrees Celsius was well above the long-term average of 27.3 degrees¹, and the highest since February 2004 (30.6 degrees). It was the equal fourth highest mean daily maximum temperature on record. The record highest was 32.0 degrees in February 1968. Maximum temperatures reached 30.0 degrees or more on 16 days, which is double the average of 8 days. They reached 35.0 degrees or above on four days, compared with the average of only one day. The highest daily maximum temperature of 38.1 degrees on 2 February was in the top 1% of records for maximum temperatures ever recorded at the Airport in February.  The record maximum temperature is 42.2 and was recorded on 1 February 1968. The lowest maximum temperature of 23.5 degrees was recorded on 7 February.

The mean daily minimum temperature of 14.8 degrees Celcius, was 1.8 degrees above the average of 13.0 degrees Celcius, and was the seventh highest on record at the airport. The record of 16.1 degrees was in 1983. The lowest temperature was 6.2 degrees on 10 February, which was the coldest since 1999, when 5.7 degrees was recorded on 20 February.

As both the maximum and minimum temperatures were well above average, the mean daily temperatures (average of daily maximum and minimum temperatures) of  22.6 degrees was well above the average of 20.1 degrees Celsius. This is the fourth warmest February mean temperature on record, with the warmest February mean being 23.5 degrees in 1983.

Rainfall:
A total of 26.2mm of rain fell at Canberra Airport in February, which is well below the average of 55.4mm². Rain fell over three days, which is also below the average of 7 days in February. There were two thunderstorms reported at Canberra Airport, in comparison to the mean number of 3 days, with no reports of hail. Other noteworthy thunderstorm activity in the ACT region was on 15 February, when thunderstorms produced local flash flooding in the Higgins area.

Rainfall across the ACT was variable, with the heaviest totals recorded for the 24 hrs to 9am on 16 February. The highest reading of 47.2mm was recorded at Tuggeranong. This is considered to have a return period of once every 10 years. Queanbeyan (NSW) recorded 64.2mm.

Other:
Strong winds were experienced on one day, which is average for February. The monthly evaporation of 243.0mm, is above the February average of 201.9mm. The mean daily sunshine of 10.9hr/day was also above the mean of 9hr/day for Febraury. There were no fogs (average 1), or frosts reported (zero average) and the average daily pressure of 1014.2hPa, is above the February mean of 1013.8hPa.  The above average relative humidity that was experienced during January, did not persist in February, with an average relative humidity of 60.2%, in comparison to the February average of 63%.

This statement has been prepared based on information available at 12 PM on 1 March 2006. Although every effort has been made to check them, it is possible that results may change as new information becomes available.

A note about deciles: Deciles are used to give an element (in this case rainfall or temperature) a ranking. Deciles are calculated by arranging the totals in ascending order (from lowest to highest) then splitting them into 10 equal groups (thus the groups are called deciles). The first group would be in decile range one, the second group in decile range two, etc up to the highest annual totals (highest 10 per cent) being in decile range 10.

¹ All temperature averages are averages from Canberra Airport, based on the period 1961 to 1990, which is a convention of the World Meteorological Organisation.

² All averages are based on the long term averages from Canberra Airport, during the period 1939 to 2006, with the exception of those stated in¹.

Further information:

Louise Tilley, NSW Climate Section, tel: (02) 9296 1555
Kenn Batt, Canberra Meteorological Office, tel: (02) 6249 6269, email: k.batt@bom.gov.au

A directory of Bureau services is available on poll fax: 1800 630 100

The latest rainfall and temperature maps are available here
Climate averages for New South Wales localities are available here
Daily Weather Observations for selected New South Wales localities are available here