Monday 3 July 2006

SYDNEY MONTHLY CLIMATE SUMMARY - NSW REGIONAL OFFICE

Sydney has coldest June in 24 years

June 2006 - Main Points:

• Coldest June since 1982.
• Wettest June since 1991, total of 176.8mm.
• Average daytime maximum temperature of 17.0°C lowest since 1989 (when 16.7°C).
• Many cold nights, especially western suburbs - Richmond recording 16 frosts.
• Below average sunshine, 5.2 hours/day lowest since 1998 when 4.2 hours/day.

Temperatures:    In a significant departure from recent months, well below average temperatures were recorded in Sydney during June, ending the run of 5 consecutive Junes with above average temperatures.  It was also the first month since March 2005 with significantly below average temperatures.  The average monthly mean temperature (the average of the daily maximum and minimum temperatures) of 12.9°C was well below the historic average¹ of 13.6°C and the coldest since 1982 (when 12.7°C).  Days were cool to cold with the average maximum day-time temperature of 17.0°C at Observatory Hill being below the historic average of 17.7°C and the lowest since 1989.  The average maximum temperature at the more elevated locations of Terrey Hills and Springwood was a degree or so cooler.  Cloudy, showery conditions and prevailing S-SW winds contributed to the cold weather.

Nights were also cold with the average minimum temperature at Observatory Hill being 8.7°C, almost one degree below the historic average, and the lowest for 6 years.  Nights were particularly cold in the western suburbs where Richmond's average minimum of 2.9°C was more than 2°C below the historic average. Frosts were frequent in the west with Richmond recording 16 frosts (minimum temperature 2°C or less), more than twice the June average of 7 frosts.  On the 16th the mercury fell to -2.6°C at Richmond, the lowest Metropolitan temperature for this June.

The highest temperature at Sydney (Observatory Hill) during June was 20.0°C on the 20th while the lowest temperature was 5.8°C on the 12th, the lowest June minimum for 6 years. Corresponding extremes across the Sydney metropolitan area ranged from 20.8°C at Holsworthy and Horsley Park on the 20th to -2.6°C at Richmond on the 16th.

Rainfall:   Sydney's total rainfall of 176.8mm was well above the historic average of 127.7mm and the wettest June since 1991 (when 341mm was recorded). There were 14 rain days during June the highest since 1999.  The historic average is 11 rain days. Much of the rain fell during the first week of the month when heavy showers and rain periods were associated with a low-pressure system and a strong SE air stream.   However, the heavy rain was confined to coastal suburbs with much lighter falls extending inland to the western suburbs where below average rainfall was recorded. Metropolitain rainfall for June ranged from 255mm at Cronulla and 250mm at Randwick in Sydney's east to only 30mm at St Clair and Willmot in Sydney's far west.

Rainfall over the Warragamba Dam catchment area was slightly above the June average in parts of the upper catchment around Goulburn and Bowral but below average over the remainder. June totals were in the 40 to 70mm range. Recent rainfall over Sydney's catchments can be found on the Sydney Catchment Authority web site http://www.sca.nsw.gov.au/dams/rainfall.html

Other phenomena:  Widespread fog on the 23rd and 24th closed Sydney airport for several hours with visibility reduced to 300 metres at times.  A thunderstorm on the 6th closed Sydney airport for a brief period when lightning struck the fuel depot.

Sydney Observatory Hill   (Elev 39m)

June 2006

Historic average

June 2005

 17.0

 17.7

 19.2

 8.7

 9.6

 10.6

 12.9

 13.6

 14.9

 176.8

127.7#

79.0

 14

11

 10

 5.2

6.9

6.0

Average relative humidity at 3pm (%)

 62

56

59

Number of thunderstorms

 1

1

0

Number of windy days*

 3

4

3

  Parramatta (Elev 55m)

   Richmond  (Elev 19m)

     Camden       (Elev 79m)

Terrey  Hills # (Elev199m)

Springwood #

(Elev 362m)

June 2006

Historic average

June 2006

Historic average

June 2006

Historic average

June 2006

June 2006

 17.1

 17.8

 16.5

 17.7

 17.0

 17.8

 15.4

 15.4

 6.3

 7.4

 2.9

 5.2

 3.6

 4.3

 7.5

 5.3

 11.7

 12.6

 9.7

 11.5

 10.3

 11.1

 11.5

10.3

 107.2

 76.4

 48.8

 56.4

 50.6

 52.4

 113.8

 41.6

 11

 10

 13

 8

 11

 8

 13

 14

June 2006

All years

June 2006

All years

June 2006

All years

June 2006

June 2006

 20.0 (20th)

  26.9   (1931)

 19.5  (20th)

25.5  (2004)

19.3  (1st)

26.8  (1931)

 17.8  (20th)

 18.8 (15th)

 5.8 (12th)

  2.1   (1932)

 2.0

 (15th)

0.8  (2000)

-2.6  (16th) 

-6.7  (1932)

 4.3  (15th)

 -0.3 (15th)

12.2 (5th)

  9.7   (1899)

  13.3  (5th,11th)

10.5  (1975)

12.9  (5th) 

10.0  (1935)

 11.4  (5th)

 10.5 (11th)

 49.6 (6th)

150.6  (1991)

 32.2  (6th)

209.1  (1991)

107.7  (1964)

 27.8  (6th)

 10.8 (6th)

SSW @ 76  (3rd,11th)*

S @ 135  (1956)

-

 SSW @ 57  (3rd)

  W @ 109 (1945)

 SSW @ 68  (3rd)

-

This statement has been prepared based on information available at noon on 03/07/06. 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.

Further information: Contact Mike De Salis 02 9296 1542, email: reqnsw@bom.gov.au

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

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Daily Weather Observations for selected New South Wales localities are available here