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

Jump to:  Extremes  Summaries  Notes  the top

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

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

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

 


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


Notes

This statement has been prepared based on information available at 11 am on Monday, 3 December 2007. 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.