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Historical rainfall, frost and heat maps for the South West Land Division

Historical rainfall, frost and heat maps for the South West Land Division (SWLD) for the period 1975 to 2023

Historical rainfall maps

The baseline time period of 1975-2023 is used for rainfall because since the mid-1970s, rainfall in the 2 wettest months (June and July) has declined by up to 20% in the SWLD, with reductions in the number of rain days and the rainfall amounts in extreme events (Indian Ocean Climate Initiative, 2012). The decline in winter rainfall is attributed to fewer days with low pressure weather systems and the persistence of high-pressure systems (Indian Ocean Climate Initiative, 2012). Since 2000, the overall trend in rainfall is for drier seasons (decile 1-3) than wetter (decile 8-10).       

Total rainfall

Rainfall decile maps

  • Annual: January to December
    pdf (2.09 MB)
    View map
  • April to October
    pdf (7.39 MB)
    View map
  • May to October
    pdf (7 MB)
    View map
  • May to October including information on significant climate drivers for that season
    pdf (2.19 MB)
    View map
  • November to March
    pdf (7.29 MB)
    View map

6 seasons based on the Noongar calendar

Thanks to the South West Aboriginal Land and Sea Council for their support.

4 seasons based on the Gregorian calendar

  • Summer (December to February)
    pdf (1.95 MB)
    View map
  • Autumn (March to May)
    pdf (2.06 MB)
    View map
  • Winter (June to August)
    pdf (2.13 MB)
    View map
  • Spring (September to November)
    pdf (1.99 MB)
    View map

Heat severity and occurrence 1975-2023

Heat severity and occurrence maps are provided for the months August to October, 1975-2023 for the SWLD.

Heat stress (days above 30°C in August to October) is a limiting factor to crop yield and puts stress on livestock.

Map showing the average number of days above 30°C for the South West Land Division of Western Australia for the period August to October 1975-2023, ranging from 0 days to 13-16 days.
Average number of days above 30°C for August to October for the period 1975-2023.
  • Heat severity: August to October
    pdf (2.13 MB)
    View map
  • Heat occurrence: August to October
    pdf (2.21 MB)
    View map

Frost severity and occurrence

The below maps detail occurrence and severity of historical frost, where the temperature recorded is below 2°C for July to October 1975-2023. Frost severity records the minimum temperature and frost occurrence records the number of days in a month or multiple months when the minimum temperature is below 2°C.

map showing the average number of frost days (days below 2°C) for the South West Land Division of Western Australia for the period August to October 1975-2023, ranging from 0 days to 17-20 days.
Average number of frost days for August to October for the years 1975-2023.

The maps below show the average number of days below 2°C for July, August, September and October for the period 1975-2023.

Map showing average number of days below 2°C for the South West Land Division of Western Australia for July for the period 1975-2023, ranging from 0 days along the coast to 9-10 days in the wheatbelt.
Average number of days below 2°C for the South West Land Division for July 1975-2023.
Map showing average number of days below 2°C for the South West Land Division of Western Australia for August for the period 1975-2023, ranging from 0 days along the coast to 9-10 days in 3 pockets of the wheatbelt
Average number of days below 2°C for the South West Land Division for August 1975-2023.
Map showing average number of days below 2°C for the South West Land Division of Western Australia for September for the period 1975-2023, ranging from 0 days along the coast to 5-6 days in 3 pockets of the wheatbelt.
Average number of days below 2°C for the South West Land Division for September 1975-2023
Map showing average number of days below 2°C for the South West Land Division of Western Australia for October for the period 1975-2023, ranging from 0 days to 3-4 days at 5 weather stations.
Average number of days below 2°C for the South West Land Division for October 1975-2023.

Related content

  • Indian Ocean Climate Initiative (2012) Milestone report 4, Project 1.2 South-west Western Australia’s regional surface climate and weather systems.
    View report

References

Indian Ocean Climate Initiative (2012) Milestone report 4, Project 1.2 south-west Western Australia’s regional surface climate and weather systems (Accessed 12 April 2024).