Adelaide: Climate and water

  • Total annual rainfall was below average for the third consecutive year.
  • Streamflows were low reflecting the relatively dry conditions over the region.

Schematic representation of the Adelaide region. In 2019–20, rainfall was 558 mm, less than average for the third consecutive year. Streamflow in Onkaparinga River in 2019–20 was 39 GL compared to the average value of 70 GL. Soil moisture was 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 Adelaide region generally experiences mild winters and warm, dry summers. Most of the rainfall in the region falls from May–September. Rainfall can be unreliable and infrequent during summer (December–February).
  • Streamflow in the region's rivers generally reflects the distribution of rainfall throughout the year. Most of the streamflow and storage inflow occurs during the winter months (June–August) and very little streamflow is observed during the dry summer months (December–February).

 

Climate conditions

Rainfall

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

 

  • Total area-averaged rainfall for the year was 558 mm, less than the mean value of 630 mm.
  • Rainfall was 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 in the first half 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.

 

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

 

  • Rainfall was above average in January–February 2020 and April 2020. All other months had average or below-average rainfall.

 

Actual evapotranspiration

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

 

  • Total area-averaged actual evapotranspiration was below average across most of the region.
  • Evapotranspiration was below average during July 2019–January 2020 due to low water availability following low rainfall in the latter half of 2019.
  • Evapotranspiration was average over large parts of the region during February–June 2020 due to increased water availability following higher rainfall in the first half of 2020.

 

Soil moisture

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

 

  • Soil moisture in the root zone (0–1m depth) was average across most of the region.
  • In July 2019, root-zone soil moisture was already average following a relatively wet winter in 2019. Dry conditions during the entire latter half of 2019 meant that by December 2019, root-zone soil moisture was below average over most of the region.
  • By June 2020, soil moisture was above average over large parts of the region following higher rainfall in the first half of 2020.
  • More information on soil moisture distribution across the Adelaide region is available in the Australian Landscape Water Balance.

 

Streamflow responses

Map of key gauging stations. North Para River at Yaldara, station number A5050502, is in the northern part of the region near the town of Gawler. Onkaparinga River at Houlgrave, station number A5030504, is in the central part of the region.
Figure C5 Key flow gauging stations along the main rivers within the Adelaide region

 

  • Onkaparinga River provides the major inflows into Mount Bold Reservoir—the region's largest storage.
  • Flow along the North Para River is unregulated and not influenced by diversions for consumptive use.

 

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

 

  • Annual streamflows in the region's major rivers were well below average reflecting the relatively dry conditions throughout the year, particularly during the latter half of 2019. For example, total annual flow in the Onkaparinga River at Houlgrave (Station A5030504) was 39 GL compared to the average value of 70 GL.
  • Annual streamflow in the North Para River was very low for the second consecutive year. No flow occurred in the river for almost the entire summer–autumn period.
  • The higher rainfall periods during the first half of 2020 had only a minor effect on streamflow. The very dry soil moisture conditions across the region during most of the year meant much of the rainfall that occurred was soaked up by the soil.