Monday, 2 December 2013 - Seasonal Climate Summary for Sydney  - Product code IDCKGC25L0

Sydney in spring 2013: Warmest spring on record

• Warmest spring on record
• Above average rainfall, fewest rain days since 2002
• Severe early-season bushfires during September and October

Extremes Records Summaries Important notes the top

Rainfall - Dry start, wet end

Sydney Observatory Hill recorded 266.6 mm of rain during spring, slightly above the historical average of 229.3 mm. Most of the rain fell during November, which was the wettest for Sydney since 1984, while the September-October total was half the historical average. The rain fell over 24 rain days, well below the historical average of 34 days and the fewest since 2002, but nine days recorded at least 10 mm (average 6 days) and four recorded at least 25 mm (average 2 days).

Most of the rain during the season was associated with complex surface troughs and low pressure systems, with thunderstorm activity generating heavier local falls. Across the Sydney basin, heavy daily totals included:

• 88.2 mm at Randwick on 17 September
• 47.4 mm at Mona Vale on 28 October, with shortlived storms causing local flash flooding
• 45 mm at Audley on 10 November
• 53.6 mm at Wahroonga on 12 November
• 96 mm at Avalon on 16 November
• 67 mm at Prospect Reservoir on 19 November
• 42.3 mm at Badgerys Creek on 23 November

Temperature - Warmest spring on record

Sydney Observatory Hill recorded an average maximum temperature of 24.7 °C during spring, 2.8 °C above the historical average and the warmest spring on record. Temperatures were warmest during the first part of the season, with the warmest September on record followed by the second-warmest October, associated with sunny conditions, westerly winds, and several very hot days. In contrast, above average rainfall resulted in closer to normal temperatures during November, which was the coldest month of the season.

Only seven days during the season failed to reach at least 20 °C (average 31 days), well below the previous record of 11 cool days in 2002 and 1988. There were ten days of at least 30 °C (average 4 days) and seven days above 32 °C (average 2-3 days); these included the second-earliest 31 °C day on record (7 September) and the third-warmest October day (37.3 °C on the 10th)

The average minimum temperature was 15.1 °C, 1.7 °C above the historical average and the equal-third-warmest on record. Nights were warm throughout the season, but particularly during September, which was the warmest on record for mean minimum temperatures as well as breaking the record for 9am temperatures on two occasions during the month.

The mean temperature for Sydney Observatory Hill was consequently 19.9 °C, 2.2 °C above the historical average and the warmest spring on record, 0.3 °C higher than the previous record in spring 1988. Notably, this follows the warmest winter on record for Sydney, recorded earlier this year.

Some sites had their highest spring mean daily maximum temperature on record.

Other phenomena - Strong winds and bushfires

The prevailing winds were variable during the season; September and October were dominated by anomalously northerly-westerly winds, contributing to warm, dry conditions, before a shift to cooler southerlies and easterlies during November. Strong winds caused damage on several occasions during September, with a tornado causing substantial damage in Hornsby during November.

The hot, dry, windy conditions contributed to substantial early-season bushfire activity during September and October. Notably, in the Springwood/Winmalee area of the Blue Mountains, two homes were destroyed during bushfires on 10 September, before a period of sustained bushfire activity between 17-23 October destroyed an additional 193 houses, as well as power, rail, and tourism infrastructure.

For further information, please see the relevant Monthly Climate Summary or Monthly Weather Review.

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top