Thursday 3 January 2008 - Annual Climate Summary for Sydney extremes - Product code IDCKGC3xx0

 

Year 2007: Sydney has record warm nights

Summary

  • Average annual minimum temperature was highest in 149 years of record
  • Many warm nights, total of 61 nights when minimum temperature exceeded 20°C (3rd highest on record)
  • 12th consecutive year with average or above average maximum temperatures
  • 11th consecutive year with above average minimum temperatures
  • Wettest year since 1998
  • Stormiest year since 1963
  • Slightly above average sunshine hours

Rainfall

Sydney's total annual rainfall of 1499.2 mm recorded at Observatory Hill, was above the historic annual average of 1215 mm and ranks in the highest 20% of totals.  It was the wettest year in Sydney since 1998 (when 1649 mm recorded). There were 133 rain days during the year which is slightly below the historic average of 138 rain days.  About half the annual rainfall (730 mm) occurred during Sydney's wet winter, with the majority of the winter total falling in June. The western suburbs were drier than the coast but still close to the historic average. Annual rainfall extremes ranged from 1672 mm at Turramurra on the north shore to 929 mm at Box Hill in the north west and 947.2 mm at Campbelltown in the far south west.

The above average annual rainfall can be attributed to Sydney's very wet winter and the above average rainfall in November and December, resulting from a late establishing La Nina event in the Pacific Ocean.

Sydney's Warragamba Dam catchment also received above average rainfall during 2007 with totals ranging from 1155 mm in the lower catchment to 639 mm at Goulburn Airport in the upper catchment. Over the year storage capacity rose from 36% in early January to 61% at the end of December.

Maximum temperatures

Sydney experienced generally mild to warm days during 2007. The average maximum (daytime) temperature at Observatory Hill was 22.7°C, significantly above the historic average1 of 22.1°C and ranks as equal 9th warmest year since records commenced in 1859. Average maximum temperatures in the western suburbs were about 1°C warmer than coastal suburbs due mainly to the absence of cooling sea-breezes during the warmer months.

While Sydney recorded significantly above average maximum temperatures during most months of 2007, June was the noteable exception recording well below average temperatures (the coldest June for 18 years). The above average temperatures in Sydney are consistent with above average temperatures experienced throughout NSW. Sydney has now experienced 12 consecutive years with average or above average maximum temperatures. This is a pattern consistent with the observed global trend of rising temperatures.

The highest temperature at Sydney Observatory Hill during 2007 was 38.7°C on 21 January while the highest in the Sydney metropolitan area was 42.0°C at Badgerys Creek also on 21 January.

Minimum temperatures

Average minimum (night-time) temperatures at Sydney Observatory Hill were well above the historic average1 during 2007.  The average minimum of 15.2°C was 1.0°C above the historic average1. This is the warmest average annual minimum temperature on record for Sydney since records commenced in 1859. The previous highest was 15.1°C in 1988. This is now the 11th consecutive year at Observatory Hill with above average minimum temperatures. Sydney's western suburbs recorded annual minimum temperatures several degrees cooler than along the coast but still significantly above the historic average. Sydney Airport recorded its highest average annual minimum temperature on record with 15.0°C, the previous highest was 14.9°C in 1998.

Warm nights persisted from January to March and again in December. There were 61 nights when the temperature did not fall below 20°C, the 3rd highest ever recorded. Normally Sydney would expect only 36 nights above 20°C (based on standard normal period 1961−1990).

The lowest temperature at Sydney Observatory Hill during 2007 was 3.7°C on 17 July while the lowest in the Sydney metropolitan area was −3.5°C at Badgerys Creek also on 17 July.

Wind

There were 75 strong wind days recorded at Sydney Airport during 2007 compared to the historic average of 63 days. Only 6 gales were recorded during the year (average 11 gales). The highest wind gust in metropolitan Sydney during 2007 was 109 km/h from the west at Camden on 5 March. The prevailing direction at coastal sites was NW-NE for about 40% of the time.

Other phenomena

Thunderstorms: Sydney recorded 33 thunderstorms during 2007 compared to the historic average of 28 storms. This is the highest number of storms since 1963 when 51storms were recorded. One of the most severe storms occurred on 4 April when 96 mm was recorded at Rose Bay with marble size hail and major local flooding of houses and shops. However, the most severe was the supercell of 9 December which produced heavy rain, squally winds and giant hail up to 7cm size from Blacktown to Wahroonga with unconfirmed reports of 11cm size hail in Cherrybrook. The total damage bill was close to $200 million. The period from about 19 November to 10 December was Sydney's most stormy and humid 3 week spell for about 20 years with many reports of local flash flooding during storms, especially in inner west suburbs.

Sunshine: the amount of sunshine for Sydney during 2007 averaged 7.4 hours per day which is slightly above the historic average of 7.2 hours per day.  However, monthly averages varied considerably from only 4.7 hours per day in June to 9.4 hours per day in January, the sunniest January for 22 years.

Bushfires: burnt out several hundred hectares of bushland in Ku-ring-gai Chase National Park north of Sydney during January and October, however, there were no reports of property being destroyed.

Further information

Mike De Salis
Climate Information Officer
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
42.0°C at Badgerys Creek on 21 Jan
Warmest days on average
Highest mean daily maximum temperature
24.5°C at Penrith Lakes
Coolest days on average
Lowest mean daily maximum temperature
21.9°C at Terrey Hills
Coldest day
Lowest daily maximum temperature
10.8°C at Springwood on 27 Jun and 19 Aug
Coldest night
Lowest temperature
−3.5°C at Badgerys Creek on 17 Jul
Coolest nights on average
Lowest mean daily minimum temperature
10.8°C at Campbelltown (Mount Annan)
Warmest nights on average
Highest mean daily minimum temperature
15.2°C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature
23.0°C at Sydney Olympic Park on 22 Jan
23.0°C at Sydney (Observatory Hill) on 4 Mar
Wettest overall
Highest total rainfall

1671.7 mm at Turramurra and 1666.6 mm at Castle Cove

Driest overall
Lowest total rainfall
929.0 mm at Box Hill and 947.2 mm at Campbelltown (Mount Annan)
Wettest day
Highest daily rainfall
156.6 mm at Ruse on 11 Feb
Highest wind gust
109 km/h at Camden Airport on 5 Mar

Records

Record highest annual mean daily minimum temperature
Mean daily minimum
temperature
for 2007 (°C)
Previous annual
highest
Years of
record
Normal
annual
Sydney Airport
15.0
14.9 in 1998
78
13.1
Sydney (Observatory Hill)
15.2
15.1 in 1988
149
14.2



Record lowest annual temperature
Lowest temperature
in 2007 (°C)
Previous annual
lowest
Years of
record
Normal
annual
Prospect Dam −0.6 on 17 Jul −0.5 in 2005
43
12.2



Summaries for the Sydney area

Summary statistics for 2007
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean
for
2007
Diff
from
normal
Highest
for
2007
Mean
for
2007
Diff
from
normal
Lowest
for
2007
Total
for
2007
Normal
annual
total
Rank
of
2007
Fraction
of annual
normal
Sydney (Observatory Hill) 22.7 +0.6 38.7 21 Jan 15.2 +1.0 3.7 17 Jul 1499.2 1215.4 high 123%
Camden Airport 23.8 +0.2 41.1 21 Jan 10.9 +0.7 −3.1 17 Jul 1023.4 771.0 high 133%
Parramatta North 23.7 +0.5 41.0 21 Jan 12.9 +0.8 0.0 17 Jul 1370.6 963.9 very high 142%
Richmnd 23.7 0.0 40.9 12 Jan 11.6 +0.5 −3.4 17 Jul 1051.2 810.3 high 130%
Springwood* 22.2 38.1 12 Jan 11.5 −2.6 17 Jul 1188.7 1067.5 normal 111%
Terrey Hills* 21.9 39.7 21 Jan 13.3 0.2 17 Jul 1302.2

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

Additional climate data for Sydney for Year 2007
 

Year 2007

Normal for year

Number of rain days

133

138

Average sunshine hours per day*

7.4

7.2

Average humidity at 3pm (%)

57

57

Number of thunderstorms

33

28

Number of windy days*

75

63

Number of gales*
6
11

* recorded at Sydney Airport.  Windy day defined as average speed of 40−62 km/h or more at synoptic times and gale 63−87 km/hr.


Notes

This statement has been prepared based on information available at 9am on Thursday 3 January 2008. Some checks have been made on the data, 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.