Friday 1 June 2007 - Monthly Climate Summary for Sydney extremes - Product code IDCKGC1xx0

Sunny, dry and second warmest May on record for Sydney

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Summary

  • Second warmest May on record and warmest since 1958
  • 5th consecutive May with above average maximum temperatures
  • 18 days when temperature exceeded 22°C, second highest after 1958
  • 6th driest May on record
  • Equal sunniest May on record at 8.0 hours per day, same as 1982 and 2004

Temperatures

Sydney has experienced its second warmest May on record.  The average maximum (daytime) temperature at Observatory Hill was 22.4°C, or 2.1°C above the historic average1of  20.3°C.  The warmest May on record was in 1958 with an average maximum temperature of 22.7°C.  Sydney also experienced 18 days when the temperature exceeded 22°C, the second highest on record after 19 days in 1958.  The historic average is only 5 days.  Much of the western suburbs recorded similar average maximum temperatures to the coast except for Richmond and the elevated locations of Terrey Hills and Springwood which recorded average maximums around 1°C cooler than coastal suburbs.  Several locations in the metropolitan area had their highest average maximum temperature on record for May (see table of records below).

Along the coast, nights were also well above average for May.  The average minimum temperature at Sydney (Observatory Hill) of 13.7°C was 1.7°C above the historic May average1 and the second highest ever recorded in May.  The highest was 14.0°C in 1989.  However in far western suburbs, night-time temperatures were much closer to the historic average with Camden Airport recording an average minimum of 7.3°C, only 0.1°C above the historical average and the lowest in the Sydney area.

The very mild conditions during May were in part due to the persistent high pressure ridge over NSW causing mainly clear skies and prevailing winds from the NW quadrant. There was also a lack of any cool southerly changes reaching Sydney, as well as above average sea surface temperatures along the NSW coast.  Although a single month with near record high temperatures cannot be directly attributed to climate change, it forms part of a trend to above average temperatures which is consistent with what is expected under global warming.

The highest temperature at Sydney (Observatory Hill) during May was 28.6°C on the 3rd while the lowest temperature was 7.8°C on the 31st.  Corresponding extremes in the Sydney area ranged from 28.8°C at Sydney Airport on the 3rd to 0.6°C at Richmond on the 25th and Camden Airport on the 27th and 31st.  The maximum temperature of 27.5°C at Camden Airport on the 3rd was the highest on record for May.

Some sites had their highest May temperature on record.

Some sites had their highest May mean daily maximum temperature on record.

Some sites had their warmest May night (highest daily minimum temperature) on record.

Rainfall

The total May rainfall of only 9.8 mm at Sydney Observatory Hill was well below the historic May average of 122.3 mm and the 6th lowest since records commenced in 1859.  There were only 4 rain days during the month, 4th lowest on record, and well below the average of 12 rain days.  Rainfall totals for May generally showed little variation over the Metropolitan area with a tendency of slightly higher totals in far western suburbs than along the coast.  The only exception were some locally higher totals on the far northern beaches.  Metropolitan rainfall ranged from 105 mm at Avalon on the northern beaches to only 8.2 mm at Randwick in the east. The total rainfall at Sydney Airport of 11.4 mm was the lowest since 1957.  Significant rain events during May were on the 9th (affected mainly northern beaches) and on the 17th when widespread light rain was caused by a low-pressure trough and an in feed of moisture from the tropical north-west of the continent.

The Warragamba Dam catchment area received May totals of around 40−60 mm which is close to the historic average of 45−65 mm.  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

Other phenomena

Sydney received plentiful sunshine during May.  The average of 8.0 hours per day was equal highest on record and the same as May 1982 and May 2004 (records commenced in 1931).  The persistent high-pressure ridge over NSW and low moisture levels contributed towards the predominantly clear skies.  Two fogs were recorded during May (on 14th and 17th) briefly closing Sydney airport. On the 17th, visibility was reduced to 200 metres in the CBD area and 100 metres at Richmond.  Although there was a general lack of rain during the month, very heavy showers and flash flooding occurred in the northern beaches on 9 May where Avalon recorded 94 mm in about 2 hours.

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		 28.8°C at Sydney Airport on the 3rd
Warmest days on average
Highest mean daily maximum temperature		 23.3°C at Sydney Olympic Park
Coolest days on average
Lowest mean daily maximum temperature		 21.2°C at Springwood
Coldest day
Lowest daily maximum temperature		 15.4°C at Springwood on the 10th
Coldest night
Lowest temperature		 0.6°C at Richmond on the 25th
0.6°C at Camden Airport on the 27th and 31st
Coolest nights on average
Lowest mean daily minimum temperature		 7.3°C at Camden Airport
Warmest nights on average
Highest mean daily minimum temperature		 13.7°C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature		 19.9°C at Sydney (Observatory Hill) on the 4th
Wettest overall
Highest total rainfall		 105.0 mm at Avalon
Driest overall
Lowest total rainfall		 8.2 mm at Randwick
Wettest day
Highest daily rainfall		 94.0 mm at Avalon on the 10th (24 hours to 9am)
Highest wind gust
 94 km/h at Holsworthy on the 29th

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Records for the Sydney area

Record highest May mean daily maximum temperature
Mean daily maximum
temperature
for May 2007 (°C) 		Previous highest
for May 		Years of
record		 Normal for
May
Prospect Dam

22.4

 21.5 in 1982

40

20.2
Parramatta

22.9

 22.0 in 1973

38

20.4
Bankstown Airport

22.5

 21.7 in 1982

38

20.4
Camden Airport

22.3

 21.9 in 1999

29

20.4
Riverview Observatory

21.9

 21.6 in 1947

68

19.6
 

Record highest May daily temperature
Highest temperature
in May 2007 (°C) 		Previous highest
for May 		Years of
record		 Normal for
May
Camden Airport 27.5 on the 3rd 27.4 on the 4th in 1972

29

20.4

 
Record highest May daily minimum temperature
Highest daily minimum
temperature
in May 2007 (°C) 		Previous highest
for May		 Years of
record		 Normal for
May
Parramatta 18.5 on the 4th 18.0 on the 3rd in 1987

38

10.0
 

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Summaries for the Sydney area

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

Summary statistics for the Sydney area for May 2007
Maximum temperatures
for May 2007
(°C)		 Minimum temperatures
for May 2007
(°C)		 Rainfall
May 2007
(millimetres)
Mean for
May		 Diff
from
normal		 Highest for
May
Mean for
May		 Diff
from
normal		 Lowest for
May
Total for
May		 Normal
for
May		 Rank of
May		 Fraction of
May
normal
Sydney (Observatory Hill) 22.4 +2.1 28.6 3rd 13.7 +1.7 7.8 31st 9.8 122.3 very low   8%
Parramatta 22.9 +2.5 28.4 3rd 11.3 +1.3 4.0 31st 15.4 74.4 low 21%
Camden Airport 22.3 +1.9 27.5 3rd 7.3 +0.1 0.6 27th 36.8 60.6 normal 61%
Richmond 21.4 +1.0 27.0 3rd 8.0 −0.2 0.6 25th 24.2 58.8 normal 41%
Springwood* 21.2 26.5 3rd 9.5 2.1 31st 25.8 74.1 normal 35%
Terrey Hills* 21.4 25.9 8th 12.2 7.5 23rd 16.0

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

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

May 2007

Normal for May

Number of rain days

 4

 12

Average sunshine hours per day*

 8.0

 6.0

Average humidity at 3pm (%)

 53

57 

Number of thunderstorms

 0

 1

Number of windy days*

1

 3

* recorded at Sydney Airport

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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.