Monday, 2 August 2010 - Monthly Climate Summary for Sydney - Greater Sydney - Product code IDCKGC25L0

Sydney in July 2010
Cloudy conditions continue wet winter.

• Wettest July since 2006
• Highest number of rain days since 1959
• Third lowest sunshine on record - 4.8 hours per day

An archive of previous monthly summaries for Sydney - Greater Sydney is also available, as are summaries for other states and many other climate summaries and diagnostics.

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Rainfall

Observatory Hill recorded a total July rainfall of 114.2 mm, which is twice the historical average of 56.3 mm. This was the wettest July in Sydney since 2006, when 140.2 mm of rainfall was recorded. Sydney has now experienced three consecutive months of above average rainfall.

The rain fell on 18 days, well above the average of 8.5 rain days and the largest number in over 50 years (19 days in July 1959). However, only five days had totals exceeding 5mm (average for July is 4.1), with the majority of Sydney's rainfall falling during three main events. The first occurred on the 9th (32.0 mm) when moist onshore south to southeasterly winds brought showers to the coast. The second and third events occurred on the 26th (16.0 mm) and 29th (24.2 mm), both of which were associated with the passage of an upper level trough across the state. The remainder of Sydney's rainfall fell intermittently throughout the month, and was associated with moist onshore flow generated by slow moving high pressure systems over the country.

Sydney's water storage levels have dropped 0.5% to 57.2% . Current water storage information can be found on the new Bureau of Meteorology Water Storage Beta Release web site.

Temperature

The average maximum temperature at Observatory Hill for July was 17.1 °C, which is equal to the historical average¹ of 17.1 °C. Conditions in the west were similar, with maximum temperatures at Richmond RAAF averaging 17.0 °C during July (average 17.5 °C). Conditions were coolest in the early part of the month, with maximum temperatures of just 12.1 °C on the 2nd. However, temperatures exceeding 20 °C on the 30th and 31st brought the month to a warm end and increased average temperatures across Sydney.

Observatory Hill recorded an average minimum temperature of 9.2 °C during July which is slightly above the historical average of 8.4 °C and the warmest night-time temperatures since July 2005 (9.3 °C). This is associated with the overcast conditions prevailing throughout the month.

Wind

During July, Sydney Harbour (Fort Denison) experienced prevailing westerly winds in mornings (93% of days), turning to southwesterly winds in the afternoons (55% of the time), which is average for this time of year. Just one strong wind day was recorded at Sydney Airport (on the 14th), below the historical average of four days with strong winds during July.

Other phenomena

Sunshine averaged 4.8 hours per day at Sydney Airport, well below the historical average (all records) of 6.6 hours per day. This is the lowest daily sunshine average for July since 1993 (4.4 hours per day) and the third lowest daily sunshine average for July on record. In comparison, average cloudiness was 4.7 oktas, well above the historical average of 3.2 oktas and the highest since July 1993 (4.8 oktas). Two thunderstorms (average 1) were reported at Sydney Airport, on the 20th and 25th.

Four fogs were reported at Sydney Airport during July, well above the historical average of one to two fogs and the equal highest on record (last occurence in July 1950). The most significant were on the 29th and 30th of the month, causing some flight delays and diversions. The latter event was unusually widespread, extending as far as Western Sydney (reports of visibility as low as 150m) and Brooklyn, leading to the issue of a Sydney Road Weather Alert.

Extremes

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Records

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Summaries

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

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Daily rainfall

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.

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Notes