Models indicate a neutral chance of exceeding median rainfall across the South West Land Division (SWLD) this spring (September–November 2025), meaning extreme wet or dry conditions are unlikely, but a wide range of rainfall remains possible. Temperatures are expected to be near normal.
Recent conditions:
- Nights below 2°C in August were above average, with the Department of Primary Industries and Regional Development (DPIRD) weather station Wickepin North recording the highest number of nights with 17, 6 above the average. Manypeaks recorded the coldest minimum at -4.9°C.
- August rainfall was above average, with a series of cold fronts bringing consistent rain throughout the SWLD.
- Bureau of Meteorology's (BoM) latest root zone soil water map shows average to very much above average root zone soil moisture throughout the SWLD.
Rainfall summary
Rainfall from 1 April to 31 August indicates widespread rainfall throughout the SWLD. Margaret River recorded the highest rainfall total of 1,090 mm. On the other end of the scale, Nungarin has recorded 147 mm since April.
The rainfall decile map for the same period shows decile 8-10 the majority of the SWLD, with Williams and DPIRD Narrogin weather station tracking at decile 1.
Figure 1: Rainfall (mm) totals for 1 April to 31 August 2025 in the SWLD. Margaret River has recorded the highest total of 1,090 mm, Nungarin the lowest with 147 mm.
Figure 2: Rainfall decile ranking map for 1 April to 31 August 2025 for the SWLD, indicating decile 8-9 rainfall for much of the SWLD.
Soil moisture at root zone
The current root zone soil moisture ranking (31 August) from BoM’s Australian Water Outlook is average to very much above average across the SWLD, based on percentile rankings. Root zone soil moisture is calculated as the sum of water in the Australian Landscape Water Balance model’s upper and lower soil layers, representing conditions within the top 1 m of the soil profile and indicating how current moisture compares with historical conditions for the same period.
Figure 3: Relative root zone soil moisture ranking for 31 August 2025 from BoM’s Australian Water Outlook, indicating soil moisture is average to very much above average in the SWLD.
Number of nights below 2°C
The number of nights below 2°C provides an indication of frost risk. These maps are generated using data from 332 BoM and 191 DPIRD stations. Both sets of weather stations measure air temperature in a shaded enclosure (usually a Stevenson Screen) at a height of approximately 1.2 m above the ground. A temperature of 2°C at 1.2 m is equivalent to 0°C at ground level, which is cold enough to cause significant damage to cereal crops.
In August 2025, the number of nights below 2°C was generally above the 2000-24 average. For example, the DPIRD weather station Wickepin North recorded 17 nights below 2°C, which is 6 more than the average for that period. Lowest temperature for August was at Manypeaks and a minimum temperature of -4.9°C. DPIRD’s extreme weather event tool identifies which DPIRD weather stations have recorded frost potential temperatures based on hourly data.
Figure 4: Number of days below 2°C for August 2025 for the SWLD. DPIRD’s weather station Wickepin North recorded 17 nights below 2°C.
Figure 5: Average number of nights below 2°C in August for the years 2000-24 for the SWLD. The August 2025 map is greater than these averages.
The average number of nights below 2°C for September (2000-24) shows a similar spatial pattern to the August average map, but with fewer potential frost events. Wandering, York and Newdegate have the highest number of nights below 2°C with 8 nights. With a neutral chance of above median rainfall in September – according to the majority of climate models, and a high chance of a negative Indian Ocean Dipole (which generally has average minimum temperatures in spring) the frost potential for September is normal across the SWLD.
Figure 6: Average number of nights below 2°C in September for the years 2000-24 for the SWLD. Wandering, York and Newdegate have the highest number, with 8 nights below 2°C.
French and Schultz potential yield
The potential yield map uses seasonal rainfall and decile finishes, calculated from historical data, to determine the maximum possible wheat yield under ideal conditions, without any other constraints, including water logging. This map is a valuable tool in the seasonal decision-making. Potential wheat yield is estimated using the French and Schultz potential yield model, which is expressed as:
Yield (tonnes/ha) = WUE * (stored soil water + growing season rainfall - evaporation)
WUE stands for water use efficiency, and growing season rainfall is measured from April to October. The stored soil water at the start of the growing season is estimated as one-third of the summer rainfall.
The map generated uses rainfall data from 1 April to 24 August and assumes a decile 5 rainfall from 25 August to 31 October, with a WUE value of 20 kg/ha/mm. The lowest yield potential is 1.4 t/ha at Nungarin.
Figure 7: Potential yield map, using French and Schultz equation, for the SWLD 24 August 2025. Lowest yield potential is for Nungarin at 1.4 t/ha.
Seasonal Bushfire Outlook Spring 2025
The seasonal bushfire outlook for spring 2025 released by the Australian and New Zealand Council for fire and emergency services (AFAC) highlights an increased fire risk for parts of the Pilbara and Kimberley regions of Western Australia and for parts of South Australia and Victoria. The higher risk of fire in WA follows increased fuel growth following seasonal rains, coupled with the predicted warmer than normal temperatures and higher likelihood of below average rainfall through spring.
Figure 8: AFAC Seasonal Bushfire Outlook for Spring 2025, indicating higher fire risk for parts of the Pilbara and Kimberley region of Western Australia, parts of South Australia and Victoria.
Rainfall outlooks
Three-month and single-month rainfall outlooks are derived from a range of national and international climate models. The outlooks are presented as the probability of rainfall being below, above, or neutral relative to the median rainfall (note: A neutral outlook suggests that extreme wet or dry events are less likely, and a wide range of rainfall amounts remains possible). To provide a more localised perspective, the SWLD has been divided into 2 regions, allowing for tailored rainfall outlooks specific to each area.
Figure 9: Rainfall outlooks are in 2 sections based on location in the SWLD ̶ first group includes Central West and Central Wheatbelt forecast districts, second group includes Lower West, South West, Great Southern, South Coastal and South East Coastal forecast districts.
Rainfall outlooks for the Central West and Central Wheatbelt forecast districts of the SWLD
Single month
A summary of 14 national and international models shows that 9 models indicate chances of exceeding median rainfall for September 2025. This neutral model consensus applies for the rest of the year. A neutral outlook suggests that extreme wet or dry events are less likely, and a wide range of rainfall amounts remains possible.
Figure 10: Single month model summaries for rainfall for the Central West and Central Wheatbelt forecast districts of the SWLD up to December 2025. Model consensus is for neutral chance of exceeding median rainfall for September, October, November and December.
Three month
A summary of 17 national and international models shows that for spring, September to November, 9 models indicate neutral chances of exceeding median rainfall. There is also model consensus for neutral chance for November 2025 to January 2026 and summer December 2025 to February 2026. A neutral outlook suggests that extreme wet or dry events are less likely, and a wide range of rainfall remains possible. There is no model consensus for October to December.
Figure 11: Model summary of rainfall outlook for the Central West and Central Wheatbelt forecast districts of the SWLD up to summer, December 2025 to February 2026. Model consensus is for neutral chances of exceeding median rainfall (except for October to December).
Rainfall outlooks for the Lower west, South West, Great Southern, South Coastal and South East Coastal forecast districts of the SWLD
Single month
A summary of 14 national and international models shows that 9 models indicate chances of exceeding median rainfall for September 2025. This neutral model consensus applies until the end of the year. A neutral outlook suggests that extreme wet or dry events are less likely, and a wide range of rainfall amounts remains possible.
Figure 12: Single month model summaries of rainfall for the Lower West, South West, Great Southern, South Coastal and South East Coastal forecast districts of the SWLD up to December 2025. The majority of models are indicating neutral chance of exceeding median rainfall until the end of the year.
Three month
A summary of 17 national and international models shows that 10 models indicate above median rainfall for spring, September to November. Model consensus is for neutral chance of exceeding median rainfall up to summer, December 2025 to February 2026. A neutral outlook suggests that extreme wet or dry events are less likely, and a wide range of rainfall remains possible. It is important to note that forecast reliability decreases with longer lead times.
Figure 13: Three month model summaries for rainfall for the Lower West, South West, Great Southern, South Coastal and South East Coastal forecast districts of the SWLD up to summer, December 2025 and February 2026. Model consensus is for neutral chance of exceeding median rainfall.
Important disclaimer
The Chief Executive Officer of the Department of Primary Industries and Regional Development and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.
Copyright © State of Western Australia (Department of Primary Industries and Regional Development), 2025
