Friday 1 June 2007 - Monthly Climate Summary for Sydney extremes - Product code IDCKGC1xx0
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Sydney has experienced its second warmest May on record. The average maximum (daytime) temperature at Observatory Hill was 22.4°C, or 2.1°C above the historic average1of 20.3°C. The warmest May on record was in 1958 with an average maximum temperature of 22.7°C. Sydney also experienced 18 days when the temperature exceeded 22°C, the second highest on record after 19 days in 1958. The historic average is only 5 days. Much of the western suburbs recorded similar average maximum temperatures to the coast except for Richmond and the elevated locations of Terrey Hills and Springwood which recorded average maximums around 1°C cooler than coastal suburbs. Several locations in the metropolitan area had their highest average maximum temperature on record for May (see table of records below).
Along the coast, nights were also well above average for May. The average minimum temperature at Sydney (Observatory Hill) of 13.7°C was 1.7°C above the historic May average1 and the second highest ever recorded in May. The highest was 14.0°C in 1989. However in far western suburbs, night-time temperatures were much closer to the historic average with Camden Airport recording an average minimum of 7.3°C, only 0.1°C above the historical average and the lowest in the Sydney area.
The very mild conditions during May were in part due to the persistent high pressure ridge over NSW causing mainly clear skies and prevailing winds from the NW quadrant. There was also a lack of any cool southerly changes reaching Sydney, as well as above average sea surface temperatures along the NSW coast. Although a single month with near record high temperatures cannot be directly attributed to climate change, it forms part of a trend to above average temperatures which is consistent with what is expected under global warming.
The highest temperature at Sydney (Observatory Hill) during May was 28.6°C on the 3rd while the lowest temperature was 7.8°C on the 31st. Corresponding extremes in the Sydney area ranged from 28.8°C at Sydney Airport on the 3rd to 0.6°C at Richmond on the 25th and Camden Airport on the 27th and 31st. The maximum temperature of 27.5°C at Camden Airport on the 3rd was the highest on record for May.
Some sites had their highest May temperature on record.
Some sites had their highest May mean daily maximum temperature on record.
Some sites had their warmest May night (highest daily minimum temperature) on record.
The total May rainfall of only 9.8 mm at Sydney Observatory Hill was well below the historic May average of 122.3 mm and the 6th lowest since records commenced in 1859. There were only 4 rain days during the month, 4th lowest on record, and well below the average of 12 rain days. Rainfall totals for May generally showed little variation over the Metropolitan area with a tendency of slightly higher totals in far western suburbs than along the coast. The only exception were some locally higher totals on the far northern beaches. Metropolitan rainfall ranged from 105 mm at Avalon on the northern beaches to only 8.2 mm at Randwick in the east. The total rainfall at Sydney Airport of 11.4 mm was the lowest since 1957. Significant rain events during May were on the 9th (affected mainly northern beaches) and on the 17th when widespread light rain was caused by a low-pressure trough and an in feed of moisture from the tropical north-west of the continent.
The Warragamba Dam catchment area received May totals of around 40−60 mm which is close to the historic average of 45−65 mm. Recent rainfall in Sydney's catchments can be found on the Sydney Catchment Authority web site at: http://www.sca.nsw.gov.au/dams/rainfall.html
Sydney received plentiful sunshine during May. The average of 8.0 hours per day was equal highest on record and the same as May 1982 and May 2004 (records commenced in 1931). The persistent high-pressure ridge over NSW and low moisture levels contributed towards the predominantly clear skies. Two fogs were recorded during May (on 14th and 17th) briefly closing Sydney airport. On the 17th, visibility was reduced to 200 metres in the CBD area and 100 metres at Richmond. Although there was a general lack of rain during the month, very heavy showers and flash flooding occurred in the northern beaches on 9 May where Avalon recorded 94 mm in about 2 hours.
Mike De Salis
NSW Climate Services Centre
Bureau of Meteorology
Phone (02) 9296 1555
Email mikede@bom.gov.au
Hottest day Highest temperature |
28.8°C at Sydney Airport on the 3rd |
---|---|
Warmest days on average Highest mean daily maximum temperature | 23.3°C at Sydney Olympic Park |
Coolest days on average Lowest mean daily maximum temperature | 21.2°C at Springwood |
Coldest day Lowest daily maximum temperature |
15.4°C at Springwood on the 10th |
Coldest night Lowest temperature |
0.6°C at Richmond on the 25th 0.6°C at Camden Airport on the 27th and 31st |
Coolest nights on average Lowest mean daily minimum temperature |
7.3°C at Camden Airport |
Warmest nights on average Highest mean daily minimum temperature |
13.7°C at Sydney (Observatory Hill) |
Warmest night Highest daily minimum temperature |
19.9°C at Sydney (Observatory Hill) on the 4th |
Wettest overall Highest total rainfall |
105.0 mm at Avalon |
Driest overall Lowest total rainfall | 8.2 mm at Randwick |
Wettest day Highest daily rainfall | 94.0 mm at Avalon on the 10th (24 hours to 9am) |
Highest wind gust |
94 km/h at Holsworthy on the 29th |
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Record highest May mean daily maximum temperature | |||||
---|---|---|---|---|---|
Mean daily maximum temperature for May 2007 (°C) |
Previous highest for May |
Years of record |
Normal for May |
||
Prospect Dam |
22.4 |
21.5 | in 1982 |
40 |
20.2 |
Parramatta |
22.9 |
22.0 | in 1973 |
38 |
20.4 |
Bankstown Airport |
22.5 |
21.7 | in 1982 |
38 |
20.4 |
Camden Airport |
22.3 |
21.9 | in 1999 |
29 |
20.4 |
Riverview Observatory |
21.9 |
21.6 | in 1947 |
68 |
19.6 |
Record highest May daily temperature | ||||||
---|---|---|---|---|---|---|
Highest temperature in May 2007 (°C) |
Previous highest for May |
Years of record |
Normal for May |
|||
Camden Airport | 27.5 | on the 3rd | 27.4 | on the 4th in 1972 |
29 |
20.4 |
Record highest May daily minimum temperature | ||||||
---|---|---|---|---|---|---|
Highest daily minimum temperature in May 2007 (°C) |
Previous highest for May |
Years of record |
Normal for May |
|||
Parramatta | 18.5 | on the 4th | 18.0 | on the 3rd in 1987 |
38 |
10.0 |
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In the following table, certain key sites have been highlighted to make them easier to identify.
Summary statistics for the Sydney area for May 2007 | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Maximum temperatures for May 2007 (°C) |
Minimum temperatures for May 2007 (°C) |
Rainfall May 2007 (millimetres) |
||||||||||
Mean for May |
Diff from normal |
Highest for May |
Mean for May |
Diff from normal |
Lowest for May |
Total for May |
Normal for May |
Rank of May |
Fraction of May normal |
|||
Sydney (Observatory Hill) | 22.4 | +2.1 | 28.6 | 3rd | 13.7 | +1.7 | 7.8 | 31st | 9.8 | 122.3 | very low | 8% |
Parramatta | 22.9 | +2.5 | 28.4 | 3rd | 11.3 | +1.3 | 4.0 | 31st | 15.4 | 74.4 | low | 21% |
Camden Airport | 22.3 | +1.9 | 27.5 | 3rd | 7.3 | +0.1 | 0.6 | 27th | 36.8 | 60.6 | normal | 61% |
Richmond | 21.4 | +1.0 | 27.0 | 3rd | 8.0 | −0.2 | 0.6 | 25th | 24.2 | 58.8 | normal | 41% |
Springwood* | 21.2 | 26.5 | 3rd | 9.5 | 2.1 | 31st | 25.8 | 74.1 | normal | 35% | ||
Terrey Hills* | 21.4 | 25.9 | 8th | 12.2 | 7.5 | 23rd | 16.0 |
* new stations, no historic average temperatures available and no historic average rainfall available for Terrey Hills.
Additional climate data for Sydney (Observatory Hill) for May 2007 | ||
---|---|---|
May 2007 |
Normal for May |
|
Number of rain days |
4 |
12 |
Average sunshine hours per day* |
8.0 |
6.0 |
Average humidity at 3pm (%) |
53 |
57 |
Number of thunderstorms |
0 |
1 |
Number of windy days* |
1 |
3 |
* recorded at Sydney Airport
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This statement has been prepared based on information available at noon on Friday 1 June 2007. The data has been quality controlled, 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.