Sydney Monthly Climate Summary: Winter and August 2006
Mild, wet winter for Sydney

Friday 1 September, 2006

In Brief

Winter 2006 - Main Points:

• Above average temperatures during winter (but still coolest winter since 2000).
• 9th consececutive winter with above average temperatures.
• Average maximum temperature ranked 13th highest.
• Total rainfall 403 mm, wettest winter since 1999.
• Below average sunshine.

August 2006 - Main Points:

• Average maximum temperature 5th highest on record at 19.8°C.
• There were 25 days when temperature exceeded 18°C (2nd highest on record).
• Mild days but cool nights, especially in western suburbs.
• 15 frosts at Richmond (historic average 8 frosts).
• Close to average rainfall and sunshine.

Details

Winter 2006

Rainfall:   Sydney Observatory Hill recorded its wettest winter since 1999 with a total of 403 mm since 1st June, well above the historic winter average¹ of 307 mm.   Most of the rain fell in June and July and was heaviest along the coast with far western and north-western suburbs recording below average rainfall.  There were 40 rain days, the highest since 1998 and well above the historic average of 31 rain days.  Suburban rainfall totals for winter varied greatly across the Metro area, ranging from a high of 558 mm at Cronulla in Sydney's south to a low of only 61 mm at St Clair in the far west.

Temperatures:   Although Sydney had its coldest June in 24 years, the return of above average temperatures in July and August produced an average winter temperature of 13.7°C (the average of daytime and night-time temperatures), or slightly above the historic average¹ of 13.4°C. Sydney has now experienced 9 consecutive winters with above average temperatures.

Day-time temperatures were particularly mild with the average maximum temperature of 18.2°C ranking 13th highest for winter since records commenced in 1859. Persistent sunny days and lack of any significant cool changes contributed to the mild temperatures. Sydney recorded 53 days during winter when the temperature exceeded 18°C, compared to the historic average of 29 days.

The highest temperature at Sydney Observatory Hill during winter was 25.5°C on 17 August while the coolest night was 5.8°C on 12 June and 9 July. Corresponding extremes across the Sydney metropolitan area ranged from 26.5°C at Camden on 17 August to a low of −3.3°C at Richmond on 9 July.

August 2006

Rainfall:    The total monthly rainfall of 86 mm was slightly above the historic August average of 81.4 mm. There were 11 rain days, which is also slightly above the historic average of 10 rain days.  Much of the rain fell during the first week of the month. While some southern coastal suburbs received falls of over 100 mm, several far western suburbs recorded only 10 - 20 mm.  Metropolitan rainfall totals ranged from 114 mm at Cronulla in Sydney's south to only 12 mm at St Clair in the far west.

Rainfall in the Warragamba Dam catchment area during August was very light and patchy with only 10 - 20 mm recorded over the whole catchment.  Recent rainfall in Sydney's catchments can be found on the Sydney Catchment Authority web site at: http://www.sca.nsw.gov.au/dams/rainfall.html

Temperatures:   August was a mild month in Sydney with above average temperatures. The average maximum temperature at Observatory Hill was 19.8°C, well above the historic average¹ of 18.2°C and ranking 5th highest since records commenced in 1859.  At more elevated locations of Terrey Hills and Springwood maximum temperatures were 1 or 2°C cooler than the rest of the city.  There were 25 days when the temperature exceeded 18°C at Observatory Hill, the second highest ever recorded in August with August 2005 recording 26 days over 18°C.  The historic average is 16 days.

Although nights were cold early in the month, milder conditions followed, with the average minimum temperature at Observatory Hill of 10.0°C being 0.6°C above the historic average.  However, in far western suburbs, nights were significantly colder and below the August average.  At Richmond the average minimum of 3.5°C was 1.4°C below the historic average and nearly 7°C colder than coastal suburbs.  There were 15 frosts (minimum temperature 2°C or less) at Richmond, nearly twice the historic August average of 8 frosts.

The highest temperature at Sydney Observatory Hill during August was 25.5°C on the 17th while the lowest was 6.9°C on the 3rd.  Corresponding extremes across the Sydney metropolitan area ranged from 26.5°C at Camden on the 17th to −2.6°C at Richmond on the 9th.

Other phenomena:   Sunshine hours were close to average.  There were 2 thunderstorms during August, both producing hail.  On 15 August heavy hail accumulated to a depth of several centimetres in the inner west and CBD area.  On 4 August a water spout and tornado caused damage to buildings at La Perouse in Sydney's south-east.

Sydney Observatory Hill   (Elev 39 m)

August

Winter

2006

Historic average

2005

2006

Historic average

2005

 19.8

18.2

 19.9

 18.2

17.7

 19.4

 10.0

9.4

 9.2

 9.3

9.1

 9.7

 14.9

13.8

 14.5

 13.7

13.4

 14.5

86.0

81.4#

 1.6

403.0

307.3

 143.4

11

10

 3

40

31

 20

7.8

7.9

 8.6

6.3

6.9

 7.4

Average relative humidity at 3pm (%)

49

 50

 42

55

 53

 52

Number of thunderstorms

2

1

 0

3

 3

 0

Number of windy days

2

 4

 4

8

 13

 10

  Parramatta (Elev 55 m)

   Richmond  (Elev 19 m)

     Camden       (Elev 79 m)

Terrey Hills # (Elev199 m)

Springwood #

(Elev 362 m)

August 2006

Historic average

August 2006

Historic average

August 2006

Historic average

August 2006

August 2006

 19.8

 19.0

 19.4

 18.9

 20.0

 19.0

17.9

18.5

 6.9

 7.0

 3.5

 4.9

 3.9

 3.8

8.4

6.2

 13.3

 13.0

 11.5

 11.9

 12.0

 11.4

13.1

12.4

 48.0

 56.7

 30.4

 45.8

 23.6

 45.2

45.4

18.2

 11

 8

 7

 8

 7

 8

12

5

August 2006

All years

August 2006

All years

August 2006

All years

August 2006

August 2006

25.5 (17th)

31.3   (1995)

25.2  (22nd)

30.6  (1995)

25.5  (17th)

32.8  (1953)

23.7  (22nd)

24.9  (17th)

6.9

(3rd)

2.7   (1872)

3.4

 (3rd)

0.7  (1996)

−2.6

(9th)

−4.0  (2005)

4.8

 (1st)

2.0  (8th)

12.3 (4th)

9.1  (1872)

12.6

(4th)

11.0  (1996)

13.3
(2nd)

7.8  (1938)

10.8 (4th)

11.9  (4th)

40.2 (5th)

 327.6  (1986)

 31.8

(5th)

 293.0  (1986)

 18.8 (5th)

 199.6  (1986)

22.8 (5th)

 8.0  (5th)

W @ 72   (9th)*

W @ 113  (1981)

-

WSW @ 65  (9th)

  W @ 111 (1962)

SSW @ 55   (25th)

-

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 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.

¹Averages: Historic average temperatures for Observatory Hill and Richmond are based on the period 1961 to 1990 which is a convention of the World Meteorological Organisation.  Average temperatures for Parramatta are based on all available data, 1968 - 2005 and Camden 1972 - 2005.  Rainfall averages and extremes for Observatory Hill are based on all years of record 1859 - 2005.

Further information: Contact Mike De Salis 02 9296 1555, email: reqnsw@bom.gov.au

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