Tuesday, 4 January 2011 - Monthly Climate Summary for Sydney - Greater Sydney - Product code IDCKGC25L0

Sydney in December 2010: Warm start to summer

• Above average maximum temperatures.
• 14th consecutive year with abover average minimum temperatures.
• Above average rainfall.

Extremes Records Summaries Important notes the top

Rainfall

Sydney recorded 83.2 mm during December, which is slightly above the historical average of 77.8 mm (all years of record). This was the wettest December since 123.2mm were recorded in 2007, the only other December this decade with above average rainfall. The rain fell on ten days, which is close to the historical average of eleven days. Rainfall was heighest in the Blue Mountains, with totals exceeding 150mm at Valley Heights and Springwood, while Campbelltown experienced its wettest December since 1971.

The majority of the rain fell as a result of moist onshore flow at the beginning of the month, with a total of 48.6mm occurring over the 1st and the 2nd, reaching 50mm at Valley Heights on the 1st. Smaller falls were recorded on the 17th (7.6 mm), associated with the passage of a low pressure trough, the 20th (4.8 mm) associated with a low pressure system near Tasmania, and on the 27th (17mm) as a result of a low pressure trough.

Sydney's water storage is currently at 72.5% of capacity. This is an increase of 10% from November levels (61.3%), and 20% higher than at the end of 2009 (52.6%). Current water storage information can be found on the new Bureau of Meteorology Water Storage web site.

Temperature

The average maximum temperature at Sydney Observatory Hill was 25.8°C which is above the historical December average of 25.2°C (all years of record). This is slightly warmer than December 2009 (25.4°C) but cooler than the average of 25.9°C in December 2008. Temperatures were close to average throughout the month at Observatory Hill, with three days exceeding 30°C (equal to the average) and a max of 31.3°C but only one day below 20°C (19.9°C on the 27th). The warmest day of the month was New Years Eve, with temperatures up to 35.9°C in western regions. However, western regions were cooler on average than the coastal areas, with below average maximums at Parramatta, Bankstown and Camden during the month.

Minimum temperatures averaged 18.9°C during December, which is well above the historical average of 17.5°C but cooler than December 2009 (19.0°C). The last time Observatory Hill had below average minimums in December was in 1996 (17.1°C). Twenty-two warm nights (minimum temperature >= 18°C) were recorded, which is well above the December average of 14 nights. In particular, nine consecutive warm nights occurred between the 2nd and 10th of the month, with the warmest December minimum since 2005 on the 10th (22.8°C). Later in the month, a cold snap saw the night-time temperature at Sydney Observatory Hill plummet to 13.3°C (20th), which was the coldest night-time temperature for Sydney in December since 2004.

Wind

Coastal Sydney experienced prevailing northeasterly to southeasterly winds during December, with a frequency of 87% from this direction at 3pm, which is slightly above average for this time of year. The highest wind gust at Sydney Airport was 80 km/hr from the south on the 26th, associated with a low pressure trough, with a maximum wind gust anywhere in Sydney of 81km/hr at Kurnell on the 20th.

Other phenomena

No thunderstorms were reported at Sydney Airport during December (historical average 3.6 storms), with only three storms in the entire Sydney metropolitan region. Sunshine at Sydney Airport averaged 8.2 hours per day during the month, above the historical average of 7.9 hours per day, although 3pm cloudiness was slightly above the historical average of 4.5 oktas (4.7 during December 2010).

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top

Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with »» are part of a longer accumulation, which is marked like this on the final day. Values over 100 mm have been rounded to the nearest whole millimetre. Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.

Extremes Records Summaries Important notes the top