Climate change in the Hyden area, Western Australia

Page last updated: Thursday, 22 July 2021 - 1:11pm

The Department of Primary Industries and Regional Development provides this agri-climate profile of historical and projected climate information to support farm business managers in their response to a changing climate in the Hyden area of Western Australia.

Why this information is important

Climate change and climate variability have affected Western Australian (WA) broadacre crop and animal production over recent decades, with significant reductions in rainfall and increased frost risk. Producers have been able to meet these challenges by adopting innovative farming systems to maintain farm profitability and sustainability. Future climate change will present further opportunities and challenges for producers.

Records shows that rainfall decreased and temperatures increased over the last century. Projections for the south west of WA indicate further rainfall declines and higher temperatures.

The grainbelt of WA contributes more than $4.5 billion to WA’s economy per year. Hyden is located 340 kilometres east of Perth on the eastern edge of the central grainbelt. This agri-climate profile provides an analysis of records and projections for a range of climate variables relevant to farm businesses in the Hyden area.

Changes at a glance

The observed trends in Hyden’s climate include:

  • increased maximum temperatures
  • increased number of days with extreme temperatures
  • increased number of frost days in June and October
  • reduced growing season rainfall, and
  • more-variable and later starts to the growing season.

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What the records show

Shifts in climate were observed for Hyden in the mid-1970s, then again around 2000. Therefore, the analyses are for the periods 1931–1974 (43 years), 1975–2018 (43 years) and 2000–2018 (18 years).

Rainfall

  • Total annual rainfall has remained relatively unchanged from 1931–1974 to 1975–2018.
  • Growing season rainfall (April–October) declined by 2% from 1931–1974 to 1975–2018, with a further 8% decline in the period from 2000–2018.
  • The chance of two consecutive drought years (decile 3 growing season rainfall or below) has decreased from 8% in 1931–1974 to 5% in 1975–2018.
April to October rainfall for Hyden for the years 1931-2018, showing a decline in the average rainfall
April to October rainfall for Hyden for the years 1931-2018.

June rainfall is significantly reduced in 1975–2018 and 2000-2018.

Average mean monthly rainfall for Hyden for years 1931-2018.
Average mean monthly rainfall for Hyden for years 1931-2018.

There has been no significant change in the number of large rainfalls (greater than 5mm) and the number of rain days, apart from in June. The difference between periods in these figures is less important than the variability between years.

Average monthly number of rainfall above 5 mm in Hyden 1931-2018.
Average monthly number of rainfall above 5 mm in Hyden 1931-2018.
Average number of rain days per month for Hyden 1931-2018.
Average number of rain days per month for Hyden 1931-2018.

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Temperature

Since the mid-1970s, mean monthly maximum temperatures have significantly increased for all months except September and December.

Mean maximum monthly temperature for Hyden for the years 1931 to 2018.
Mean maximum monthly temperature for Hyden for the years 1931 to 2018.

Minimum temperatures have significantly increased in February and November.

Mean minimum monthly average temperatures for Hyden 1931-2018.
Mean minimum monthly average temperatures for Hyden 1931-2018.

The number of days with extreme temperatures, or maximum temperature above 35 degrees Celsius (˚C), has significantly increased in the periods from January to April and October to December.

Average number of days above 35C in Hyden 1931-2018.
Average number of days above 35C in Hyden 1931-2018.

The number of frost days, or days with minimum temperature below 2˚C, has significantly increased in June and October. This indicates that the frost risk around flowering has increased. The average date of the last frost was 7 October in 1931–1974 and 15 October in 1975–2018.

Average number of days below 2C for Hyden for the years 1931-2018.
Average number of days below 2C for Hyden for the years 1931-2018.

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Projected changes

The following projections are for the period 2035–2064. Projections were obtained using an intermediate-emissions scenario (A2) and downscaled data from the CSIRO Global Climate Model CCAM (CMIP3).

Rainfall

Projections are for decreased autumn–winter rainfall and increased summer rainfall.

Bar chart showing decreased monthly rainfall in autumn and winter, and increases in summer
Figure 10 Historical monthly rainfall for 1939–1974 and 1975–2010 and monthly projected rainfall for 2035–2064

Temperature

Projections are for increasing average monthly maximum temperatures.

Bar chart showing a continued rise of mean monthly maximum temperatures
Figure 11 Historical mean monthly maximum temperature for 1939–1974 and 1975–2010 and projections for 2035–2064

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What are the agronomic implications?

  • The start of the growing season has generally remained unchanged.
Break of the season for Hyden for the years 1931-2018.
Break of the season for Hyden for the years 1931-2018.
  • Later and more variable breaks of season will increase production risk for crops and pastures. Declining autumn rainfall means crops needs to be established at the earliest opportunity. Conservation of out-of-season rain is gaining importance. Effective control of summer weeds and stubble is becoming more important.
  • Killing summer weeds can increase the amount of water available in the soil for the growing season. Kill summer weeds as quickly and effectively as possible after they emerge. The first paddocks to treat are those that have the most water and nitrogen to lose (for example, pulse stubbles, long fallow).
  • Frost remains a significant risk in winter and spring, and frost risk around flowering has increased significantly. Cold conditions and later starts to the growing season may increase lamb mortality.

What are the options for adapting to climate change?

We provide information and technical support for making changes at the incremental, transitional and transformative levels. A general guide is available for each major enterprise and for soil and water resources:

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