Tuesday, 1 December 2009 - Seasonal Climate Summary for Sydney - Greater Sydney - Product code IDCKGC15L0

Spring nights warmest on record in Sydney

• Very warm nights - highest average minimum temperature on record
• 24 warm nights (minimum greater than 18 °C), highest on record
• 8th warmest average maximum temperature
• Slightly below average rainfall
• Average sunshine

Details Extremes Records Summaries Important notes the top

Rainfall

Sydney metropolitan area recorded slightly below average rainfall during spring. Observatory Hill's total of 209.4 mm for the season compares to historic average¹ of 230 mm. Over 86% of Sydney's spring rain fell in about 3 weeks in October with September and November remaining very dry. There were only 26 rain days during the season, well below the historic spring average of 35 rain days. The wettest suburbs in spring were in Sydney's north, the highest total being 265 mm at North Rocks in northwest Sydney. The driest region was the far west where the lowest total for the season was 79.4 mm at Penrith Lakes AWS. The wettest single day was 119.4 mm at Frenchs Forest on 26 October.

The majority of Sydney's spring rainfall fell during October associated with moist onshore winds. Both September and November recorded less than 20 mm each and were associated with the stabilising effect of persistent high pressure systems.

Sydney's Warragamba Dam catchment area recorded below average spring rainfall with most totals between 100 and 140 mm over the catchment area. Storage levels have fallen over spring from 59% on 1 September to currently 55% of total capacity. Recent rainfall and current levels in Sydney's 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 very warm spring with above average temperatures over the whole of the metropolitan area. The average maximum (daytime) temperature at Observatory Hill during spring was 23.5 °C, which is 1.6 °C above the historic average¹ of 22.9 °C. It ranks as Sydney's 8th warmest spring out of 150 years of record. Sydney's warmest spring was in 2002 (average maximum 24.2 °C). Maximum temperatures were a few degrees warmer in the western suburbs. Both Prospect Reservoir (42.0 °C) and Riverview Observatory (40.5 °C) set new records for their highest spring temperature.

Sydney's spring nights were the warmest ever recorded. The average minimum at Observatory Hill of 15.4 °C was 2.0 °C above the historic spring average¹ of 13.4 °C. The previous highest average spring minimum temperature was 15.3 °C set in 2007. There was also 24 warm nights during spring (minimum greater than 18 °C), the highest ever recorded at Observatory Hill. During a typical spring there is normally only 7 nights above 18 °C. Record high minimums were not confined to the coast with numerous inland suburbs also reporting record high average spring minimums. The above average temperatures were mostly due to only weak cool changes reaching Sydney, especially in September and November, and heatwave conditions in November caused by a slow moving high pressure system.

The highest temperature at Sydney Observatory Hill during spring was 40.4 °C on 22 November while the highest over the Greater Sydney area was 42.5 °C at Sydney Airport also on 22 November. The lowest temperature at Observatory Hill during spring was 8.9 °C on 10 October while the lowest over the Greater Sydney area was 2.0 °C at Camden Airport AWS also on 10 and 11 September and at Campbelltown on 11 September.

Wind

The prevailing afternoon wind direction in coastal Sydney during spring was E-NE for 50% of the time, above the normal frequency of 42% from this direction. The strongest wind gust was 94 km/h at Penrith Lakes AWS on 20 November during a thunderstorm.

Other phenomena

A major duststorm with strong winds hit Sydney during the morning of 23 September producing a blood red sky and reducing visibility to 400 metres over much of the city. The dust, originating from South Australia and western NSW, was the worst duststorm in Sydney since 1942. Sydney had 12 thunderstorms during spring (historic average 9 storms). Very heavy rain on 25 October associated with slow moving thunderstorms caused flash flooding in parts of the inner west, North Shore, Audley Weir and Wolli Creek at Earlwood. On 20 November, two houses caught fire after being struck by lightning during a severe thunderstorm. A downburst from the same storm caused extensive damage to houses at Church Point in northern Sydney.

Sydney recorded a spring average of 7.8 hours of sunshine per day, which is normal for the season. However, this was a combination of plentiful sunshine in September (average 8.8 hours per day) and cloudy conditions in October (average 6.8 hours per day).

Details Extremes Records Summaries Important notes the top

Details Extremes Records Summaries Important notes the top

* incomplete record, total rainfall not available.

Details Extremes Records Summaries Important notes the top