Rainfall across the majority of the Canberra region was very much above average for 2010–11 (Figure C1). The total area–averaged rainfall over the Canberra region during 2010–11 was 1,141 mm, well above the mean annual rainfall of 794 mm. The above average rainfall in the Canberra region saw the region's storages increase from 114,648 ML at 30 June 2010 to 201,252 ML at 30 June 2011. Significant flooding occurred in December 2010, with several stations observing their highest daily December rainfall on record.
Figure C1. Map of annual rainfall deciles for the Canberra region during 2010–11
Rainfall across the region ranged from more than 1,600 mm along the western boundary to less than 1,000 mm over the northeast of the region (Figure C2).
Figure C2. Map of total annual rainfall for the Canberra region during 2010–11
The above average rainfall observed in the Canberra region is consistent with the wet year experienced across much of eastern Australia. These wet conditions were a result of a very strong La Niña event in the Pacific Ocean. La Niña conditions persisted from September 2010 through to March 2011. The spring time rainfall (September to November) was very likely influenced by warm ocean temperatures around the Australian continent, which brought above average rainfall to much of southern Australia, particularly the southeast.
The area-averaged monthly rainfall was above the long-term average from July 2010 to March 2011, with four of these months receiving rainfall totals above the 90th percentile (Figure C3). December was a particularly wet month in the Canberra region, with an area-averaged rainfall total of over 200 mm, almost three times the long-term average for the month. December 2010 ranked as the second-wettest December in 111 years of record and February 2011 was the third-wettest February on record.
The La Niña event concluded in April 2011 and below-average rainfall conditions prevailed across the Canberra region for the final months of the reporting period (April to June 2011).
Figure C3. Graph of total monthly rainfall for the Canberra region during 2010–11 compared with the long–term average and percentiles for the region
Figure C4. Map of annual evapotranspiration deciles for the Canberra region during 2010–11
Evapotranspiration was higher along the western boundary of the region (Figure C5), which corresponds to the areas of higher rainfall (Figure C2).
Figure C5. Map of total annual evapotranspiration for the Canberra region during 2010–11
The Canberra region experienced mean annual daytime temperatures close to the long-term average during the 2010–11 reporting period (Figure C6).
Figure C6. Map of annual maximum daily temperature deciles for the Canberra region during 2010–11
Mean maximum daily temperatures across the region ranged from more than 18 °C in the north around the city of Canberra to less than 14 °C in the southwest of the region (Figure C7).
Figure C7. Map of annual mean maximum daily temperature for the Canberra region during 2010–11
La Niña events are typically associated with cooler than average temperatures, particularly in eastern parts of Australia from October to April. Monthly mean daytime temperatures for the Canberra region were, with the exception of January, below the long-term average between November 2010 and April 2011 (Figure C8), which is consistent with the typical effect of the La Niña on daytime temperatures.
Figure C8. Graph of average monthly maximum daily temperature for the Canberra region during 2010–11 compared with the long-term percentiles for the region