December 2014 Review - Sydney

Above average figures from October and November carried on into December in 2014, making for a very warm end to the year in Sydney. Based on Bureau of Meteorology records, Sydney Airport saw both the average minimum and maximum sit more than 1.5C above the long term figures. Rain was also above average. Storms in the early part of the month helped the Airport record its highest December total since 1992.

The averages from the past few years are shown below against the long term figure.

December averages at Sydney Airport for the period 2009-2014 plus the long term average

December 2014 saw the warmest start to a December in recent memory as daily maximums hovered around 30C for each of the first eight days. The average maximum then sat at 30.4C. It dropped to as low as 27.0C, but climbed slightly by the New Year. Bureau of Meteorology figures were a little higher than my calendar day recordings, but the 19.2C and 27.3C averages still weren't that close to the overall record figures of 19.9C and 29.5C from 1990 and 2005, respectively.

Despite the warm start, the hottest day wasn't seen until the second last day of the month. Temperatures exceeded expectations then in getting to 35.2C at Sydney Airport. That recording was the third highest December temperature since 2009, and the eighth highest of the past decade. The coolest day was December 12. It was only as warm as 22.0C then. This is the fourth highest such figure in the Airport's 76 year history.

The highest minimum of December 2014 was down on some figures from previous years. The 21.4C minimum on the 23rd was the second lowest respective figure since 2009. The month's overall lowest temperature of 15.6C came on the 14th. This is also the fourth highest such figure on record. Of the 76 Decembers of weather recordings at the Airport, only six managed to remain above 15C for the whole duration of the month. The previous December prior to 2014 to have done so was in 2005.

The highlight period of the month was the first eight days. As mentioned above, temperatures soared to around 30C for the whole period, but it was the storm activity that gathered the most attention. Each morning temperatures climbed while storms built west of the city. A more detailed wrap-up of the storm period can be found in one of my earlier posts. Rain totals from the eight days, as well as the rest of the month, can be seen alongside the daily extremes in the graph below.

Daily minimums and maximums against rainfall at Sydney Airport for December 2014

2014 saw the wettest start to a December at Sydney Airport since 1992, and it ended up as the wettest overall since then also. The monthly total according to Bureau methods was 116.0mm. The calendar month saw 114.4mm. Both are comfortably above the long term average of 73.6mm.

Rain fell on 14 days. The stormy week from December 2 to 8 was the longest streak and was responsible for 81.2mm of the monthly total. December 7 saw the highest daily total with 24.2mm. Other daily totals above 15mm included 21.4mm on the 4th and 16.4mm on the 6th. March and August were the only other months of 2014 to see three or more daily totals above 15mm. A good spell of dry weather was seen in the middle of the month though as the 10 days between December 13 and 22 didn't see any precipitation.

The overall average of maximum gusts was only just higher than that of 2013, 53.5km/h to 53.2km/h, but the number of maximum daily gusts above 65km/h was a little unusual. There was a total of eight daily figures above the mark. Since the start of 2013, only October of that year saw more occurrences with nine.

The strongest gust of the month, a southerly at 80km/h, came on one of the cooler days, December 11. December 27 and 28 were the only days with a maximum gust below 35km/h. The strongest gust for both was 33km/h, a southeasterly and northeasterly for each respective day.