Monday, 2 May 2011 - Monthly Climate Summary for Sydney - Greater Sydney - Product code IDCKGC15L0

Sydney in April 2011: Wettest April since 1999

• Wettest April since 1999
• Well above average rain days
• Close to average temperatures, below average in western Sydney

Extremes Records Summaries Important notes the top

Rainfall

Sydney Observatory Hill recorded 206.2 mm of rain during April, well above the historical average of 125.8 mm and the wettest April since 244.8 mm fell in April 1999. Following above average rainfall during March, this is the wettest start to Autumn since 1990. The rain fell over 17 days, above the historical average of 12 days, with eight consecutive days of rain between the 23rd and 30th.

The rain fell in two main events. The first, between the 16th and 17th, had daily falls of up to 56.8 mm at Observatory Hill and 66 mm at Sans Souci Public School. The second rainy period towards the end of the month was dominated by easterly winds giving persistent showers in Sydney, with daily totals as high as 31.4 mm at Observatory Hill on the 28th and 54 mm at Avalon (Wollstonecraft Ave) on the 25th. In total, Observatory Hill recorded eleven days with rainfall above 5 mm during the month, the equal 7th highest on record, of which seven exceeded 10 mm, more than double the historical average of 3 days.

Temperature

Maximum temperatures averaged 22.7 °C at Observatory Hill during April, slightly above the historical average of 22.4 °C. The highest daily air temperature was just 27 °C on the 9th, the coolest maximum since 2003, but only four days had maximum temperatures below 20 °C compared to the historical average of 6 days. This was anomalously warm for the Metropolitan region as all other stations recorded below average maximums, particularly in the west with temperatures as much as 1.6 °C below average at Parramatta.

Minimum temperatures at Observatory Hill were average at 14.7 °C, with generally below average minimums in western regions. As with maximums, the range was lower than usual, with the coldest night reaching 11.5 °C and the warmest 17.7 °C, compared to an average range between 10.3 °C and 19 °C. The temperature gradient across the city is likely related to the warm sea surface temperatures near the coast mitigating the cool southerly winds which caused the strong negative anomalies in the west.

Wind

Three strong wind days were reported at Sydney Airport during the month, average for April, with a maximum wind gust of 65 km/hr on the 16th, reaching 72 km/hr at Port Botany. Winds were predominantly S to SE, forming 57% of afternoon winds, slightly above average for this time of year.

Other phenomena

No thunderstorms were reported at Sydney Airport during April, below the historical average of 1-2 storms, with only one storm reported anywhere in the Metropolitan area. Sunshine averaged 6.3 hours at Sydney Airport, below the historical average of 6.9 hours, associated with the high rainfall during the month.

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