Rainfall across the Canberra region was generally very much above average for the 2011-12 year (Figure C1). The total area-averaged rainfall over the Canberra region during the 2011-12 year was 1115 mm, which is above the long-term area-averaged rainfall of 801 mm. These rainfall conditions, quite similar to the high rainfall observed during the 2010-11 year (see 2011 Account), contributed the increased inflows into the storages. As a result, water volumes in almost all the storages within the Canberra region were full or close to full capacity by 30 June 2012 (see 1.1 Storages).
Figure C1 Map of annual rainfall deciles for the Canberra region during the 2011-12 year
Annual rainfall ranged from more than 1,200 mm along the western and eastern borders of the region to less than 1,000 mm in the north including Canberra (Figure C2).
Figure C2 Map of total annual rainfall for the Canberra region during the 2011-12 year
The wet year observed in the Canberra region is consistent with the above average rainfall experienced across much of northern and eastern Australia. These wet conditions were a result of a La Niña event in the Pacific Ocean and warmer than average sea surface temperatures in the Australian region. La Niña conditions persisted from October 2011 through to March 2012.
The area-averaged monthly rainfall was generally close to the long-term average for the reporting period. The region experienced very high rainfall in November 2011, February and March 2012, with all three ranking as the third wettest on record for their respective months.
The reporting period concluded with generally close to average conditions between April and June.
Figure C3 Graph of total monthly rainfall for the Canberra region during the 2011-12 year compared with the long-term average and percentiles for the region
Figure C4 Map of annual evapotranspiration deciles for the Canberra region during 2011–12
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 2011–12
The Canberra region experienced mean temperatures very close to the long-term average during the 2011-12 year (Figure C6).
Figure C6 Map of annual mean temperature deciles for the Canberra region during the 2011-12 year
Mean temperatures across the region ranged from more than 12 °C in the northern parts of the region to less than 8 °C in the southwest of the region (Figure C7).
Figure C7 Map of annual mean temperature for the Canberra region during the 2011-12 year
Mean temperatures in the Canberra region were above average in the early part of the reporting period, with the region recording its second warmest August on record. November was also warm, with mean temperatures above the 90th percentile and almost 2°C higher than normal.
Monthly mean temperatures for the Canberra region were generally below average between October and April (Figure C8), with the exception of November. This is broadly consistent with the typical effect of La Niña on temperatures.
December 2011 and March 2012 were both below the 10th percentile, with an area-averaged mean temperature more than 1 °C below normal.
Figure C8 Graph of average monthly mean temperature for the Canberra region during the 2011-12 year compared with the long-term average and percentiles for the region