Sydney in summer 2010-11: A dry summer with very warm nights

  • Equal 2nd warmest summer on record for minimum temperatures.
  • 8th warmest summer on record for maximums.
  • 12th consecutive summer with above average temperatures.
  • Below average rainfall.

Rainfall

Sydney Observatory Hill recorded 155mm of rain during summer 2011, approximately half the historical average of 298.1mm and the driest summer since 2002/2003 (148mm). The majority of rain occured during December 2010 when 83.2mm fell, with both January and February recording well below average rainfall. However, rainfall varied significantly through the metropolitan region, with highest falls in the Blue Mountains including 326.2mm at Valley Heights.

The rain fell over 37 rain days, close to the historical average of 36 days. However, only three days above 10mm were recorded at Observatory Hill during summer compared to an average of 8 days, all of which occurred in December, with the highest daily fall of just 27.6mm on December 1. Daily totals of over 50mm were recorded at other suburban stations on December 1, December 6, January 3 and January 9, generally associated with isolated thunderstorms.

Temperature

Maximum temperatures at Observatory Hill averaged 27.2 °C during summer, 1.6 °C above the historical average of 25.6 °C. This was the 8th warmest summer on record for maximum temperatures, and the warmest summer since 2005. Temperatures warmed throughout the season, with slightly above average temperatures in December but near-record maximums in February, including a record-breaking heatwave between January 31 and February 6. The warmest day of the season was on February 5 2011, but very warm days were also experienced on the 26th-27th and 30th-31st of January.

Minimum temperatures during summer averaged 20.3 °C at Observatory Hill, 2.0 °C above the historical average of 18.3 °C. This was the equal second warmest summer on record, equal to summer 2009/10, and the 16th consecutive summer with above average minimums. Minimum temperatures were well above average throughout the season, with the 9th warmest December on record followed by the 2nd warmest January and February on record. Temperatures were particularly warm during the first week of February, with several records broken throughout the Metropolitan region for daily minimums and the numbers of consecutive warm days.

The mean summer temperature was consequently 23.8 °C, the twelth consecutive summer with above average temperatures at Observatory Hill and the 5th warmest summer on record. For more information on the warm temperatures in Sydney during February see the February Monthly Summary or Special Climate Statement 27, released 8th February.

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

Wind

Winds at Sydney Airport were predominantly easterly during summer, with 52% of 3pm winds from an E-NE direction and 88% of 3pm winds arising between NE and S. Thirteen strong wind days were observed during summer, below the historical average of 19 days, with the maximum wind gust of 91km/hr recorded due to a strong cold change on February 6.

Other phenomena

Sydney Airport recorded an average of 7.2 sunshine hours per day during summer, close to the historical average of 7.1 hours per day. Only five thunderstorms were reported at the Airport during the season, well below the historical average of 9 and the lowest frequency since summer 2002/3, with only six storms anywhere in the metropolitan region.

Further information

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(03) 9669 4057
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Extremes in summer 2010-11
Hottest day 42.2 °C at Sydney Airport AMO on 5 Feb 2011
Warmest days on average 29.6 °C at Richmond RAAF
Coolest days on average 26.7 °C at Terrey Hills AWS
Coldest day 17.5 °C at Springwood (Valley Heights) on 27 Dec 2010
Coldest night 8.8 °C at Camden Airport AWS on 21 Dec 2010
Coolest nights on average 16.9 °C at Campbelltown (Mount Annan)
Warmest nights on average 20.3 °C at Sydney (Observatory Hill)
Warmest night 27.6 °C at Sydney (Observatory Hill) on 6 Feb 2011
Warmest on average overall 24.4 °C at Sydney Olympic Park (Sydney Olympic Pk A
Coolest on average overall 22.4 °C at Springwood (Valley Heights)
Wettest overall326.2 mm at Valley Heights (Sun Valley Rd)
Wettest day52.4 mm at Winmalee (Pentlands Drive) on 1 Dec 2010
Highest wind gust 91 km/h at Port Botany (Molineux Point AWS) on 6 Feb 2011


Record highest summer daily minimum temperature
Highest daily minimum
temperature
in summer 2010-11 (°C)
Previous warmest
for summer
Years of
record
Average for
summer
Sydney (Observatory Hill) 27.6 on 6 Feb 2011 26.6 on 6 Feb 1973 153 18.3
Sydney Airport AMO 26.4 on 6 Feb 2011 25.8 on 23 Jan 2010 72 18.4
Bankstown Airport AWS 26.0 on 2 Feb 2011 25.0 on 8 Dec 1990 43 17.6
Camden Airport AWS 24.0 on 3 Feb 2011 = 24.0 on 23 Dec 2000 36 16.2
Riverview Observatory 26.2 on 6 Feb 2011 25.7 on 22 Dec 1997 28 17.2



Summary statistics for summer 2010-11
Maximum temperatures
for summer
(°C)
Minimum temperatures
for summer
(°C)
Rainfall
for summer
(millimetres)
Mean for
summer
2010-11
Diff
from
average
Highest for
summer
2010-11
Mean for
summer
2010-11
Diff
from
average
Lowest for
summer
2010-11
Total for
summer
2010-11
Average
for
summer
Rank of
summer
2010-11
Fraction of
summer
average
Badgerys Creek AWS 29.5   41.5 1 Feb 2011 17.3   10.6 22 Dec 2010 197.0
Bankstown Airport AWS 28.9 +1.2 41.6 1 Feb 2011 18.8 +1.2 12.4 20 Dec 2010 129.8 264.3 low 49%
Camden Airport AWS 29.5 +0.6 41.3 1 Feb 2011 17.2 +1.0 8.8 21 Dec 2010
Campbelltown (Mount Annan) 29.3   40.6 5 Feb 2011 16.9   8.8 21 Dec 2010
Canterbury Racecourse AWS 28.2   41.0 1 Feb 2011 18.8   11.1 21 Dec 2010 119.4
Holsworthy Control Range 28.9   41.7 1 Feb 2011 17.6   9.2 21 Dec 2010 106.2
Horsley Park Equestrian Centre AWS 29.3   41.9 1 Feb 2011 17.9   9.8 20 Dec 2010 137.4
Parramatta North (Masons Drive) 28.8 +0.9 41.0 1 Feb 2011 18.2 +1.1 11.6 21 Dec 2010 161.0 299.4 low 54%
Penrith Lakes AWS     41.8 1 Feb 2011 19.0   12.1 20 Dec 2010 89.2
Prospect Reservoir 29.5 +1.6 41.3 1 Feb 2011 18.5 +1.3 12.0 20 Dec 2010 184.2 263.6 average 70%
Richmond RAAF 29.6   40.0 5 Feb 2011 18.2   11.2 21 Dec 2010
Riverview Observatory 27.9 +1.7 41.3 5 Feb 2011 19.0 +1.8 11.8 20 Dec 2010 153.2 301.1 low 51%
Springwood (Valley Heights) 27.6   38.8 1 Feb 2011 17.3   10.0 20 Dec 2010 317.6 366.7 average 87%
Sydney (Observatory Hill) 27.2 +1.6 41.5 5 Feb 2011 20.3 +2.0 13.3 20 Dec 2010 155.0 297.1 low 52%
Sydney Airport AMO 28.0 +1.8 42.2 5 Feb 2011 20.2 +1.8 13.3 20 Dec 2010 157.4 280.3 low 56%
Sydney Olympic Park (Sydney Olympic Pk A 28.9   41.8 1 Feb 2011 19.8   13.1 20 Dec 2010 146.6
Terrey Hills AWS 26.7   40.3 1 Feb 2011 18.3   10.6 20 Dec 2010 193.2

Notes

A Seasonal Climate Summary is prepared to list the main features of the weather in Sydney - Greater Sydney using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at 10 am on Tuesday 1 March 2011. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Averages 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 20 years of record, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average 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, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Further information

Media
(03) 9669 4057
Enquiries