December 2013 Review - Sydney

2013 ended with a rather warm December for Sydney. With an average maximum of 27.3C at Sydney Airport, it was easily above the long term average of 25.7C. It was also the warmest December in the years since 2009. According to Bureau of Meteorology records prior to that, it was the warmest December since 2005. The following table shows the averages since 2009.

December averages at Sydney Airport for the period 2009-2013

While the average maximum was the highest, the average minimum was the second lowest. Only 2011's cool December was lower. However, the figure was still above the long term average of 17.5C.

The lowest temperature of the month of 13.1C came on December 6, also the second lowest in the years since 2009. The highest daily minimum of 21.6C came on December 22, right in the middle for the past 5 years. The highest temperature of the month came on December 20, a hot day that reached 37.8C. As mentioned in a previous post, this was the hottest December day since 2005. The lowest maximum of the month was shared by Christmas Eve and Christmas Day when it reached only 21.5C. This was the warmest in the years since 2009.

Number of December days at certain temperature levels for the period 2009-2013

The graph above shows that even though there was a lower number of days above 30C for December 2013 compared to 2012, which has the second warmest December average maximum since 2009, the lack of cooler days helped to maintain a higher average maximum. If we look at the days above 30C for the years 2009, 2012 and 2013, the latter actually has the highest average, also helping to increase the overall average maximum for the month. The 6 days above 30C for 2009 had an average of 31.8C while 2012's was 32.8C and 2013's was 33.7C.

The monthly rainfall recording of 56.2mm was below the long term average of 73.5mm. Almost 40% of the monthly total, 21.8mm, fell in the 24 hours to 9am on December 16. BoM recorded no sunshine at the Airport on December 24 and 25, the only 2 days of the month without any sun, with Christmas Day accounting for another 15mm of rain.

The strongest wind gust of the month was a westerly at 95km/h, recorded during the afternoon of December 5. This equalled the record for the year; the other instance on October 29. The morning of Sunday December 29 also saw strong gusts. A southerly at 89km/h was the highest recorded.