Friday, 1 June 2012 - Seasonal Climate Summary for Sydney - Product code IDCKGC15L0

Sydney in autumn 2012: A season of rainfall extremes

• Above average rainfall across the city
• Wettest day since 2007; longest dry spell since 2002.
• Close to average temperatures

Extremes Records Summaries Important notes the top

Rainfall

Sydney Observatory Hill recorded 455.2 mm of rain during autumn, above the historical average of 376.8 mm but drier than autumn 2011 (533.4 mm), with falls above average across the city. Most of the rain fell during March, which was the wettest since 1984, with totals closer to average during April and well below average during May. The rain fell over 30 rain days, below the historical average of 39 days and the fewest since 2007.

There were several rain events during the season, with falls reaching 109.4 mm at Observatory Hill and up to 134 mm at Lucas Heights during an East Coast Low on the 8th, the wettest single day for Sydney since 2007, causing flash flooding in the city. Further flash flooding was recorded in mid-April, with a 48-hour total of at least 104.8 mm at Observatory Hill to 9am on the 19th, and 2-day totals as high as 177.8 mm at Turramurra in northern Sydney. In contrast, Sydney Observatory Hill had 25 consecutive dry days between April 26 and May 20, the longest dry spell since 2002.

Temperature

The average maximum temperature at Sydney Observatory Hill during autumn was 23.1 °C, 0.9 °C above the historical average. Temperatures were generally warm during April and May, associated with dry, sunny conditions, while rainy conditions drove cooler days across the city during March.

Days were particularly warm in early April, with seven consecutive days above 25 °C for only the third time on record, while temperatures reached 29.1 °C on May 10th, the 4th warmest May day on record. While no days exceeded 30 °C during the season (average 2 days), only fifteen dropped below 20 °C (average 26), with temperatures consequently mild throughout the season.

The average minimum temperature at Sydney Observatory Hill was 14.8 °C, 0.2 °C above the historical average, while nights were generally cool throughout the city. Nights were coldest during May when conditions were clear, particularly in western Sydney, with closer to average nights during March and April. The average temperature for Sydney was consequently 18.9 °C, 0.5 °C above the historical average.

Wind

The prevailing winds at Sydney Airport were generally NW-S during the mornings, 83% of 9am winds, and S-NE during the afternoons (73%), normal for autumn. There were 18 strong wind days during autumn, the most since 18 days in autumn 2003, with a maximum wind gust of 74 km/hr on April 24.

Other phenomena

Sydney Airport recorded an average of 7.2 hours of bright sunshine during autumn, above the historical average of 6.7 hours. Seven thunderstorms were reported at the airport (average 3-4 storms), with eight reported anywhere in the Metropolitan region.

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top