Monday, 3 December 2007 - Monthly Climate Summary for Sydney extremes - Product code IDCKGC1xx0

Sydney has mild, wet and humid November

Summary

• cool to mild days with below average maximum temperatures
• very warm nights, well above average minimum temperatures (3rd highest on record)
• persistent warm nights, 15 nights with minimum temperature above 18°C (normally 5 nights above 18°C)
• well above average rainfall
• high levels of relative humidity
• close to average sunshine

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Rainfall

The total November rainfall of 170.0 mm at Sydney Observatory Hill was well above the historic November average¹ of 83.0 mm.  It was the wettest November since 1995 (when 180 mm recorded). There were 15 rain days during the month, well above the November average of 12 rain days. Unlike previous months, the heavy rain was not restricted to coastal suburbs with the western suburbs also receiving significant falls. The highest totals were recorded in western and northern suburbs while the lowest were in the south-east. Monthly totals ranged from 206.2 mm at Penrith in the far west and 198.1 mm at Carlingford in the north to a low of 94 mm at Sans Souci in the south. At Camden, the total of 167.2 mm was the highest recorded in November for the Camden area for at least 40 years.

Persistent high-pressure systems near Tasmania for most of the month caused prevailing moist E to SE airstreams on the NSW coast including Sydney. The persistent high humidity combined with slow moving low-pressure troughs and cold, unstable air in the upper atmosphere produced the above average rain during November.

The Warragamba Dam catchment received heavy rainfall during November causing storage levels to rise slowly. Monthly totals over the lower catchment were generally in the 150 - 200 mm range. However, at Katoomba (on the catchment divide) the total of 375 mm was the wettest November since 1961 and the 2nd wettest in 122 years of record. The upper catchment (near Goulburn) received around 100mm, nearly twice the monthly average. Recent rainfall in Sydney's drinking water catchments can be found on the Sydney Catchment Authority web site http://www.sca.nsw.gov.au/dams/rainfall.html.

Temperatures

Daytime temperatures in Sydney were cool to mild during November. The average maximum temperature at Observatory Hill was 23.5°C, which is slightly below the historic average¹ temperature of 23.7°C.   Sydney experienced a cool spell at the beginning of the month when cloud and rain persisted for over a week. In fact, the first 8 days were the coolest start to a November since 1984.  It was slightly warmer in the western suburbs with an average maximum temperature at Richmond of 25.4 °C. However, this is still well below the historic average by 1.1°C. The main moderating effect on temperatures were persistent cool onshore winds for most of the month. Winds were between S and E for about 70% of the time along the coast.

Night-time temperatures were well above the historic average over the whole Sydney metropolitan area during November.  The average minimum temperature of 17.5°C at Observatory Hill was 1.5 °C above the historic November average¹. This ranks as 3rd warmest for November in 148 years of record. Nights were persistently warm, especially during the second half of the month; there were 15 nights when the temperature did not fall below 18°C at Observatory Hill. Normally Sydney would expect only 5 nights above 18°C. Although average minimum temperatures were several degrees cooler in far western suburbs they were still well above the historic November average at all inland sites. At Richmond, the average minimum of 15.6°C was 1.3°C above the historic average and the highest for November since 1959.

The highest temperature at Sydney (Observatory Hill) during November was a very mild 26.4 °C on the 4th while the lowest overnight temperature was 13.9 °C on the 7th. Corresponding extremes in the Sydney metropolitan area ranged from a daytime high of 33.0 °C at Liverpool on the 4th to an overnight low of 9.3 °C at Springwood on the 6th.

Wind

There were 7 windy days as measured at Sydney Airport, compared to an average of 7.  The prevailing direction over coastal Sydney was between E and S for about 70% of the time. The highest wind gust recorded was 74 km/h at Sydney Airport on the 5th.  

Other phenomena

Associated with the above average rainfall and moist SE winds was very high humidity during the early mornings. The average relative humidity at 9am was 76% which is the highest recorded in November since computer compatible records commenced in 1955. The historic average at this time is 65%.

On the 26th, parts of the western suburbs recorded very heavy overnight rain; at Abbottsbury 64mm was recorded in 90 minutes which has an average return period of 1 in 20 years for this site. A thunderstorm with hail was reported in the Penrith area on the 14th. The amount of sunshine in Sydney varied considerably from week to week with periods of clear, sunny weather followed by cloudy, showery spells. The average daily sunshine during November was 7.8 hours per day, very close to the historic average of 7.6 hours per day.

Further information

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

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Extremes for the Sydney area

Hottest day Highest temperature	33.0 °C at Liverpool on the 14th
Warmest days on average Highest mean daily maximum temperature	26.1 °C at Penrith Lakes AWS
Coolest days on average Lowest mean daily maximum temperature	22.7 °C at Terrey Hills AWS
Coldest day Lowest daily maximum temperature	14.0 °C at Springwood on the 7th
Coldest night Lowest temperature	9.3 °C at Springwood on the 6th
Coolest nights on average Lowest mean daily minimum temperature	14.2 °C at Springwood
Warmest nights on average Highest mean daily minimum temperature	17.5 °C at Sydney (Observatory Hill)
Warmest night Highest daily minimum temperature	20.6 °C at Sydney Airport on the 19th
Wettest overall Highest total rainfall	206.2 mm at Penrith
Driest overall Lowest total rainfall	94.0 mm at Sans Souci
Wettest day Highest daily rainfall	77.0 mm at Fairfield City Farm on the 27th
Highest wind gust	74 km/h at Sydney Airport on the 5th

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Records

Record highest total November rainfall
	Total rainfall for November 2007 (mm)	Previous highest for November		Years of record	Normal for November
Camden Airport	167.2	165.6	in 1984	34	76.5

 

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Summaries for the Sydney area

Summary statistics for November 2007
	Maximum temperatures for November (°C)				Minimum temperatures for November (°C)				Rainfall for November (millimetres)
	Mean for November 2007	Diff from normal	Highest for November 2007		Mean for November 2007	Diff from normal	Lowest for November 2007		Total for November 2007	Normal for November	Rank of November 2007	Fraction of November normal
Sydney (Observatory Hill)	23.5	-0.2	26.4	4th	17.5	+1.5	13.9	7th	170.0	83.0	very high	205%
Camden Airport	25.6	-0.4	32.4	17th	14.6	+1.9	9.9	11th	167.2	73.7	highest on record	226%
Parramatta	24.8	-0.5	32.0	14th	15.4	+1.5	10.2	6th	176.6	83.9	very high	210%
Richmond	25.4	-1.1	32.3	14th	15.6	+1.3	10.8	6th	157.6	76.1	very high	207%
Springwood (elev 362m)*	23.6		29.9	14th	14.2		9.3	6th	192.4	95.0	very high	203%
Terrey Hills (elev 199m)*	22.7		27.3	14th	15.6		11.4	6th	169.0

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

Additional climate data for Sydney (Observatory Hill) for November 2007
	November 2007	Normal for November
Number of rain days	15	12
Average sunshine (hours per day)*	7.8	7.6
Average humidity at 9am (%)	76	65
Number of thunderstorms	4	4
Number of windy days*	7	7

* recorded at Sydney Airport

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Notes

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