Thursday, 1 May 2008 - Monthly Climate Summary for Sydney - Product code IDCKGC15L0

Sydney has a cool April

Summary

  • Coldest April since 1983 for mean maximum temperatures
  • Below average mean minimum temperatures
  • Average to above average rainfall
  • Below average sunshine hours

Rainfall

Rainfall in April was average to above average across the Sydney region. The official site at Observatory Hill recorded 146.6 mm which is above the historic April average1 of 126.2 mm. There were 17 rain days during April well above the April average of 12, with rain recorded 13 days in a row from the 14th through to the 26th of April. This was the longest wet spell Sydney has experienced since a 15 day wet spell in March 2001. The wet spell resulted from persistent moist on-shore south to southeasterly winds directed by a high pressure system which moved very slowly from the Bight into the Tasman Sea.

Rainfall over the metropolitan area during April was highest in eastern and northern suburbs and lowest in the west. Totals ranged from 201.4 mm at Palm Beach on Sydney's northern beaches to a low of only 20.6 mm at Camden (Brownlow Hill) in the far south west.

The Warragamba Dam catchment recorded generally light rain during April which contributed towards maintaining steady storage levels. Monthly totals over most of the catchment were around 20 - 50 mm with some isolated heavier falls of up to 183 mm at Katoomba on the catchment divide. 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

Sydney experienced a cool April, with a mean maximum temperature of 21.5 °C which is 1.7 °C below the historic April average 1 making it the coldest April since 1983. The cooler temperatures were largely due to cloud cover and showers from persistent moist south to south easterly winds. A cold change that affected much of south eastern Australia saw the maximum temperature at Sydney Observatory Hill reach only 16.8 °C on the 28th of April. This was the coldest April day in Sydney since 1999.

Across the wider Sydney region mean maximum temperatures were between 20 and 22 °C. For many locations especially in western Sydney this was 2 to 3 °C below the historic average, and in some cases record or near record low average maxima for April. At Richmond the average maximum of only 21.3 °C was 2.9 °C below normal and the coldest on record (records since 1928). Liverpool recorded its 2nd lowest average maximum temperature on record for April and the coldest since 1983.

Sydney's April mean minimum temperature of 13.9 °C was also below the historic average 1 of 15.2 °C. Generally across the Sydney region minimum temperatures were between 1 and 2 °C below the historic average. At Camden, the average April minimum temperature of 9.3 °C was the 2nd lowest since records commenced in 1972 (lowest was 8.5 °C in April 2006).

Other phenomena

Associated with the persistent cloud cover was below average sunshine hours. Sydney recorded an average of only 6.1 hours per day, well below the historic April average of 6.9 hours.

Winds were generally from the south to south east for most of the month. The highest wind gust was 78 km/hr recorded at Richmond on the 27th.

Further information

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


Extremes for the Sydney area

Hottest day
Highest temperature

29.9 °C at Penrith on the 2nd

Warmest days on average
Highest mean daily maximum temperature
22.1 °C at Campbelltown (Mount Annan)
Coolest days on average
Lowest mean daily maximum temperature
19.7 °C at Springwood
Coldest day
Lowest daily maximum temperature
15.1 °C at Springwood on the 28th
Coldest night
Lowest temperature
1.6 °C at Camden Airport on the 30th
Coolest nights on average
Lowest mean daily minimum temperature
9.3 °C at Camden Airport
Warmest nights on average
Highest mean daily minimum temperature
13.9 °C at Sydney (Observatory Hill)
Warmest night
Highest daily minimum temperature
16.8 °C at Sydney (Observatory Hill) on the 25th
Wettest overall
Highest total rainfall
201.4 mm at Palm Beach
Driest overall
Lowest total rainfall
20.6 mm at Camden (Brownlow Hill)
Wettest day
Highest daily rainfall
56.0 mm at Bexley on the 21st
Highest wind gust
78 km/h at Richmond on the 27th

 


Summaries for the Sydney area

This table is very wide and may not fit if printed.

Summary statistics for April 2008
Maximum temperatures
for April
(°C)
Minimum temperatures
for April
(°C)
Rainfall
for April
(millimetres)
Mean for
April
2008
Diff
from
normal
Highest for
April
2008
Mean for
April
2008
Diff
from
normal
Lowest for
April
2008
Total for
April
2008
Normal
for
April
Rank of
April
2008
Fraction of
April
normal
 
Sydney (Observatory Hill) 21.5 -1.7 28.7 2nd 13.9 -1.3 8.4 30th 146.6 126.2 normal 117%
Bankstown Airport 21.7 -2.0 28.9 2nd 11.3 -1.4 4.0 29th 84.2 82.9 normal 102%
Parramatta 21.4 -2.5 29.2 2nd 11.5 -1.3 5.5 29th 132.9 87.0 high 153%
Sydney Airport 21.1 -1.8 29.8 2nd 13.8 -0.3 7.5 29th 149.8 104.7 high 143%
Terrey Hills* 20.0   26.9 2nd 12.3   5.5 29th 136.4
 
Prospect Dam 21.6 -1.9 28.8 2nd 11.7 -1.5 4.5 29th 79.9 74.1 normal 108%
Liverpool 22.0 -2.9 29.0 2nd 10.6 -1.7 3.9 30th 68.8 50.6 normal 136%
Penrith Lakes * 21.8   29.9 2nd 11.8   4.8 29th 84.6 69.0 high 123%
Richmond 21.3 -2.9 29.2 2nd 10.2 -1.9 2.0 30th 54.2 70.3 normal 77%

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

Additional climate data for Sydney (Observatory Hill) for April 2008
 

April 2008

Normal for April

Number of rain days

17
12

Average sunshine (hours per day)*

6.1
6.9

Average humidity at 3pm (%)

59
59

Number of thunderstorms

1
2

Number of windy days*

4
4

* recorded at Sydney Airport


Notes

This statement has been prepared based on information available at 9 am on Thursday 1 May 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 - 2007 and Camden 1972 - 2007.  Rainfall averages and extremes for Observatory Hill are based on all years of record 1859 - 2007.

A note about deciles: Deciles are used to give an element (in this case rainfall or temperature) a ranking. Deciles are calculated by arranging the totals in ascending order (from lowest to highest) then splitting them into 10 equal groups (thus the groups are called deciles). The first group would be in decile range one, the second group in decile range two, etc up to the highest annual totals (highest 10 per cent) being in decile range 10.

Normals are long-term averages 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 for temperature and less than 30 years of record for rainfall, as they cannot then be calculated reliably.