Canberra: Climate and water

  • Total annual rainfall was below average for the third consecutive year.
  • Streamflows were very low in the latter half of 2019 reflecting the dry conditions.
  • Higher rainfall in early 2020 resulted in some streamflow recovery.

Schematic representation of the Canberra region. In 2019–20, rainfall was 596 mm, less than average for the third consecutive year. Streamflow in Queanbeyan River in 2019–20 was 9 GL compared to the average value of 40 GL. Soil moisture was below average.

For further information on the region's climate and water conditions during the 2019–20 year scroll down this page or click on the links below:

 

About the region

  • The Canberra region has a relatively dry, continental climate with warm to hot summers and cool to cold winters. Rainfall in the region is relatively uniform throughout the year with a long-term monthly average of 50–75 mm.
  • Higher streamflows in the region's rivers typically occur during winter and spring following higher runoff from partially saturated catchments in autumn and winter. Streamflows in the Murrumbidgee River can also be influenced by water diversions from the Snowy Mountain Scheme.

 

Climate conditions

Rainfall

Figure C1 Annual and monthly rainfall deciles for the Canberra region during the 2019–20 year

 

  • Total area-averaged rainfall for the year was 596 mm, less than the mean value of 791 mm, and the region's lowest since 2003–04.
  • Rainfall was very low during the latter half of 2019. The below-average rainfall throughout July–December 2019 was due to a positive phase of the Indian Ocean Dipole, one of the strongest on record, that influenced Australia's climate during this period (see the Bureau's 2019–20 Climate Report for more information).
  • There was some rainfall relief during the early part of 2020 as tropical moisture associated with warmer than average sea surface temperatures off the northwest coast of Australia moved across the continent and combined with southern cold fronts to produce high rainfall across the region.
  • Heavy rainfall associated with a coastal trough that impacted the region in early February 2020 contributed to the well above-average rainfall for that month.

 

 

Figure C2 Total monthly rainfall for the Canberra region during the 2019–20 year compared with the average and percentiles for the region

 

  • Rainfall was above average during February–April 2020. All other months had below-average rainfall.
  • Rainfall in December 2019 was the lowest on record for that month.

 

Actual evapotranspiration

Figure C3 Annual and monthly actual evapotranspiration for the Canberra region during the 2019–20 year

 

  • Total area-averaged actual evapotranspiration was well below average across almost the entire region and lowest on record over eastern parts of the region.
  • Evapotranspiration was below average during July 2019–February 2020 due to low water availability across the region following a dry year in 2018–19 (see the 2019 Account) combined with very low rainfall during the latter half of 2019.
  • Evapotranspiration was average over large parts of the region during March–June 2020 due to increased water availability following higher rainfall in the early part of 2020.

 

Soil moisture

Figure C4 Annual and monthly soil moisture deciles for the Canberra region during the 2019–20 year

 

  • Soil moisture in the root zone (0–1 m depth) was below average across the region.
  • In July 2019, root-zone soil moisture was already below average over the region following a very dry 2018–19 year. Continued dry conditions during the latter half of 2019 meant that by December 2019, root-zone soil moisture was well below average and lowest on record over almost the entire region.
  • Soil moisture was above average over large parts of the region during February–May 2020 following higher rainfall in the early part of 2020, particularly in February.
  • More information on soil moisture distribution across the Canberra region is available in the Australian Landscape Water Balance.

 

Streamflow responses

Map of key gauging stations. Molonglo River at Burbong, station number 410705, is located east of Queanbeyan, upstream of the confluence of the Molonglo and Queanbeyan River. Cotter River at Gingera, station number 410730, is in the west of the region. Queanbeyan River Upstream Googong Dam, station number 410781, is in the central east part of the region.
Figure C5 Key flow gauging stations along the main rivers within the Canberra region

 

  • The Cotter and Queanbeyan rivers contribute most of the inflows to the storages in the Canberra region.
  • Molonglo River, one of the major tributaries of Murrumbidgee River, runs through the Canberra city centre where it is dammed to form Lake Burley Griffin.

 

Figure C6 Total monthly flow for major rivers in the Canberra region during the 2019–20 year compared with the average and percentiles

 

  • Streamflows were below average for most of 2019–20 reflecting the dry conditions experienced across the region. For example, total annual flow in the Queanbeyan River upstream of Googong Dam (Station 410781) was 9 GL compared to the average value of 40 GL.
  • This was the third consecutive year of low streamflow in the region's rivers throughout most of the year.
  • Streamflow was particularly low during the latter half of 2019. During July 2019–January 2020, flow in all three rivers was below the 10th percentile for the entire 7-month period and there was no flow in the Molonglo and Queanbeyan rivers between December 2019–January 2020.
  • Some streamflow recovery occurred in early 2020, particularly during February–March 2020 following the above-average rainfall in February. Streamflow in the Molonglo River was well above the 90th percentile during March 2020 reflecting the record rainfall that occurred in February 2020 over the upper reaches of this catchment area in the southeastern part of the region.