ACT Monthly Climate Summary: August 2006
Wet and cool start but dry and warm finish to Winter in Canberra

Friday 1 September, 2006

In Brief

Winter 2006 - Main Points:

• Wet and cool start but dry and warm finish to Winter in Canberra.
• June cooler and wetter with July and August warmer and drier.
• Many warm days during Winter, 23 days of 15°C or over.

August 2006 - Main Points:

• Total rain 11.6 mm driest for August since 1995 (when 5.2 mm).
• Mild days but cold nights.
• Average maximum temperature (15.3°C) was well above average.
• Frosts were well above average.
• Well above average sunshine.

Details

Winter 2006

Rainfall:   Canberra Airport's total rainfall during Winter was 122 mm, only slightly below the historic Winter average of 129 mm.  However, the majority of the rain fell during June when 74 mm was recorded, nearly double the historic average of 39.7 mm. There were 27 rain days during winter which was just below the historic average of 28 rain days. Rainfall across the A.C.T. varied from a high of 192.0 mm at Tidbinbilla Nature Reserve to a low of 113.0 mm at Queanbeyan.

Temperatures:   The trend of above average temperatures continued during Winter, apart from the cool start in June.  The average Winter (mean daily) temperature of  7.0°C (the average of daytime and night-time temperatures) was above the historic average of 6.3°C and the 6th consecutive Winter with above average temperatures.  Canberra Airport's warmest Winter was in 2005 with an average temperature of 7.6°C.  Also of note were the 7 consecutive minimum temperatures of −2.0°C or lower (12th - 18th) which last occurred in 1984.

Day-time temperatures were particularly warm with the average maximum temperature of 13.3°C being the equal 6th highest with 1994 and 2004 (the highest ever recorded was 13.7°C in 2005).  Night time temperatures (average minimum) were slightly above average at 0.6°C (historic average 0.4°C).  Winter had 23 days equal to or greater than 15°C, which is the equal 4th highest for winter, the highest was 25 days in 2005. The highest temperature at Canberra Airport during Winter was 19.9°C on 31st of August, while the coldest night (lowest temperature) was −6.0°C on 8th of August.

Other phenomena:   Canberra had plentiful sunshine during Winter, averaging 6.5 hours per day, which was above the historic average of 5.9 hours per day.  Winter traditionally has frequent frosts and this winter was no exception with 63 frosts, slightly above the average of 57 frosts.  There were 18 fogs during Winter, slightly below the average of 21 fogs. It was also less windy with an average wind run of 135km/day compared to the long term average of 187.8km/day indicating the persistence of high pressure systems experienced over winter. The average pressure of 1024.5 hPa was substantially up on the average of 1020.1hPa. Evaporation was 176.6 mm (average 178.7).

August 2006

Rainfall:    The monthly rainfall total of 11.6 mm was well below the historic August average of 47.6 mm and equal 6th lowest with 1959.  The driest August was 2.0 mm in 1994. There were 2 rain days, well below the average of 10 rain days.  A.C.T. rainfall totals ranged from 25.6 mm at Hall to 11.0 mm at Kambah.

Temperatures:    The August average daily temperature (the average of daytime and night-time temperatures) of 7.7°C was the warmest since 1998 when 8.8°C was recorded.  The average maximum temperature at Canberra Airport was a mild 15.3°C, well above the historic average of 12.9°C and the warmest since 1991 when 16.1°C was recorded. There were 19 days with a maximum temperature of 15.0°C or greater which is the second equal highest with 1995 (highest was 23 days in 1982).  However, nights were cool to cold at Canberra Airport, the average minimum temperature of 0.1°C was 0.9°C below the historic average of 1.0°C.  The highest temperature at Canberra Airport during August was 19.9°C on the 31st while the lowest was −6.0°C on the 8th.

Other phenomena:   Canberra recorded plentiful sunshine during August with an average of 8.2 hours per day (historic average 6.9 hrs/day).  There were 26 frosts,  the highest since 1982 (when also 26).  This compares with an historic average of 18 frosts.  There were 2 fogs (average 4).  It was less windy with an average wind run of 146km per day (long term average 210km/day), only 1 strong wind day (average 3) and above average air pressure of 1023.8 hPa (historic average 1018.9hPa), all indicative of the persistence of high pressure systems during August. Evaporation for the month was 81.8 mm slightly above the average of 79.7 mm.

Canberra Airport  (Elev 578 m)

August

Winter

2006

Historic average

2005

2006

Historic average

2005

 15.3

12.9

 14.3

 13.3

12.1

 13.7

 0.1

1.0

 0.5

 0.6

0.4

 1.3

 7.7

6.9

 7.4

 7.0

6.3

 7.5

11.6

47.6#

 45.8

122

129

 205.2

2

12

 13

27

28

 30

8.2

6.9

 7.8

6.5

5.9

 6.3

Average relative humidity at 3pm (%)

45

 52

 51

54

 57

 51

Number of thunderstorms

0

1

 0

0

 1

 0

Number of windy days

1

 3

 3

4

 7

 4

  Canberra Airport   (Elev (578 m)

   Tuggeranong    (Elev 587 m)

August 2006

Historic average

August 2006

Historic average#

 15.3

 12.9

 15.4

 14.0

 0.1

 1.0

 −0.6

 0.7

 7.7

 6.9

 7.4

 7.3

 11.6

 47.6

 12.6

# 61.9

 2

 10

 2

# 10

Canberra Airport

Tuggeranong

August 2006

All years

August 2006

All years

Highest temperature (°C) and date
Warmest day

19.9
(31st)

24.0
  (1982)

  19.9
   (31st)

21.4
(1994)

Lowest temperature (°C) and date
Coldest night

−6.0
(8th)

−8.5
  (1994)

−7.1
 (8th)

−8.4
(1997)

Lowest maximum temperature (°C) and date
Coldest day

10.1
 (2nd)

3.5 
(1965)

10.2
(2nd)

5.7
(1984)

Wettest day (mm) and date

11.2
(26th)

48.4
  (1974)

 12.6
(26th)

39.0
(2003)

Maximum wind gust (km/h) and date

 W
@ 72   (9th)*

NW
@ 113  (1959)

  NW 
@ 61
(9th)

N
@ 61
(2005)

This statement has been prepared based on information available at noon on 01/09/06. Although every effort has been made to check them, it is possible that results in August and Winter 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.

Averages: Historic average temperatures are based on the period 1961 to 1990 which is a convention of the World Meteorological Organisation. Historic rainfall averages and extremes based on the period 1939 to 2005.

Further information: Contact: Owen Offler on 02 62470411 or email: climate.act@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 Australian Capital Territory localities are available here