Friday 1 June 2007 - Seasonal Climate Summary for Sydney extremes - Product code IDCKGC2xx0

Sydney has third warmest autumn on record

Summary

  • equal third warmest autumn on record
  • Sydney now experienced 10 out of last 12 years with above average maximum temperatures in autumn.
  • below average rainfall, 67% of autumn average
  • above average sunshine

Temperatures

Above average maximum temperatures were experienced over most of Sydney during autumn.  The average maximum (daytime) temperature at Observatory Hill was 23.9°C, which is well above the historic autumn average1 of 22.9°C.  This is the equal 3rd warmest autumn since records commenced in 1859;  both 1968 and 2004 also averaged 23.9°C.  The warmest autumn was last year (2006) with an average maximum temperature of  24.1°C.  This makes it the 4th consecutive autumn in Sydney with above average temperatures and 10 out of last 12 years with above average maximum temperatures in autumn.  This is consistant with the trend of global rising temperatures expected with climate change. The average maximum temperatures in the far western suburbs, such as Richmond, were close to normal for autumn.

Average minimum (night-time) temperatures over most of Sydney were also well above the historic autumn average. The average minimum at Observatory Hill of 16.1°C was 1.0°C above the historic autumn average1 and is equal 2nd highest on record (the same as 1958).  Average minimum temperatures in the western suburbs were several degrees cooler than coastal suburbs and much closer to the historic autumn average.

The highest temperature at Sydney Observatory Hill during autumn was 35.1°C on 24 March while the lowest temperature was 7.8°C on 31 May. Corresponding extremes across the Sydney metropolitan area ranged from a high of 36.7°C at Prospect Dam and Sydney Olympic Park on 3 March to a low of 0.6°C at Richmond on 25 May and 0.6°C at Camden Airport on 27 and 31 May.

Rainfall

The total autumn rainfall of 254.8 mm at Sydney (Observatory Hill) was below the historic autumn average1 of 378.7 mm. However, this still falls within the normal variability of rainfall (at 67% of normal).  There were 30 rain days, which is also below the historic average of 37 rain days.  April was the only wet month with more than half of Sydney's autumn rainfall occurring during one week at the end of April.  The highest autumn rainfall totals were along the coast while the far western suburbs recorded the lowest falls.  The highest was 553.0 mm at Avalon in Sydney's northern beaches, well above the historic autumn average of 316 mm for that site.  The lowest autumn total was 104 mm at Willmot in the far west.

Sydney's water catchments received close to average rainfall during autumn.  The Warragamba Dam catchment recorded autumn totals of 150−200 mm which is close to the historic average while the smaller Woronora Dam catchment recorded totals of 300−350 mm during autumn which is a little above the historic autumn average.

Other phenomena

Sunshine hours were slightly above average during autumn at 7.1 hours per day (historic average 6.6 hours per day).  There were 5thunderstorms recorded at Observatory Hill compared to the historic average of 4 storms for autumn.  A thunderstorm at Camden on 5 March produced wind squalls of 109 km/h. Thunderstorms caused local flash flooding in the eastern suburbs twice during April (4th and 22nd) and very heavy showers on the northern beaches on 9 May.

Further information

Mike De Salis
NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email mikede@bom.gov.au

Extremes for the Sydney area

Hottest day
Highest temperature
36.7°C at Prospect Dam and Sydney Olympic Park on 3 March
Warmest days on average
Highest mean daily maximum temperature
24.8°C at Penrith Lakes, Liverpool and Sydney Olympic Park
Coolest days on average
Lowest mean daily maximum temperature
22.8°C at Springwood
Coldest day
Lowest daily maximum temperature
15.4°C at Springwood on 10 May
Coldest night
Lowest temperature
0.6°C at Richmond on 25 May
0.6°C at Camden Airport on 27 May and 31 May
Coolest nights on average
Lowest mean daily minimum temperature
11.4°C at Camden Airport
Warmest nights on average
Highest mean daily minimum temperature
16.1°C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature
23.0°C at Sydney (Observatory Hill) on 4 March
Wettest overall
Highest total rainfall
553.0 mm at Avalon
Driest overall
Lowest total rainfall
104.0 mm at Willmot
Wettest day
Highest daily rainfall
98.0 mm at Rose Bay on 23 April
Highest wind gust
109 km/h at Camden Airport on 5 March

Summaries

 In the following table, certain key sites have been highlighted to make them easier to identify.

Summary statistics for the Sydney area for autumn 2007
Maximum temperatures
for autumn
(°C)
Minimum temperatures
for autumn
(°C)
Rainfall
for autumn
(millimetres)
Mean for
autumn
2007
Diff
from
normal
Highest for
autumn
2007
Mean for
autumn
2007
Diff
from
normal
Lowest for
autumn
2007
Total for
autumn
2007
Normal
for
autumn
Rank of
autumn
2007
Fraction of
autumn
normal
Sydney (Observatory Hill) 23.9 +1.0 35.1 24 Mar 16.1 +1.0 7.8 31 May 254.8 378.7 normal 67%
Parramatta 24.6 +1.1 36.5 3 Mar 13.8 +0.9 4.0 31 May 195.0 269.7 normal 72%
Camden Airport 24.1 +0.5 35.4 3 Mar 11.4 +0.4 0.6 27 and 31 May 186.6 213.2 normal 87%
Richmond 23.6 −0.2 35.9 3 Mar 11.8 −0.2 0.6 25 May 167.4 221.2 normal 76%
Springwood* 22.7 35.5 3 Mar 12.1 2.1 31 May 164.8 288.7 low 57%
Terrey Hills* 23.0 33.3 24 Mar 14.4 4.3 31 May 221.2

* new stations, no historic average temperatures available and no historic average rainfall available for Terrey Hills.

Additional climate data for Sydney (Observatory Hill) for autumn 2007
 

Autumn 2007

Normal for autumn

Number of rain days

 30

 37

Average sunshine hours per day*

 7.1

6.6

Average humidity at 3pm (%)

 59

 59

Number of thunderstorms

 5

 4

Number of windy days*

 11

 10

* recorded at Sydney Airport


Notes

This statement has been prepared based on information available at noon on Friday 1 June 2007.  The data has been quality controlled, but it is possible that results will change as new information becomes available.

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 - 2006 and Camden 1972 - 2006.  Rainfall averages and extremes for Observatory Hill are based on all years of record 1859 - 2006.

Normals are long-term means based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of "normal" rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, normal in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of normal shows how much rain has fallen this time as a percentage of the long-term mean.