Regional predictions


Changes in temperature and rainfall

As shown in the graphs below, by 2035 the annual maximum temperature in Manjimup is predicted to increase by 0.6 to 1.0C. Monthly maximums will increase most during May through to September. It is also projected that the number of days above 40°C will increase from 3.8 to 5.3.

Annual rainfall is predicted to fall by 5-9%, particularly during winter. However, winter rainfall has already declined by 15% since 1988, suggesting existing predictions may be underestimating impacts on southwest WA.

Manjimup temp and rainfall

Potential effects on crops

  • Warmer winters leading into spring may reduce the winter crop window
  • Quality of summer leaf crops will be impacted by high temperatures
  • Reduced winter rainfall will impact on run-off available for storage and irrigation eg a 10-15% decrease in rainfall can halve run-off

Click HERE for a table showing the effects of changes in average temperature of +1oC, +2oC, +3oC, +4oC as well as the impact of 5 days over 35oC for major crops grown in Manjimup.

Note : These descriptions relate to the temperatures that the crops experience and not to changes in monthly average temperatures. An increase of 1oC in monthly average temperature can easily mean increases of 4oC or more on particular days.