Dept of Primary industries and Regional Development graphic header

Seasonal Climate Outlook

August 2026

Summary

For the South West Land Division (SWLD) climate models indicate below median rainfall August to October. Both daytime and night-time temperatures are expected to be warmer than normal for August to October and spring, September to November 2026.

Recent conditions

Rainfall in July was very much below average for the SWLD.
July maximum temperatures were very much above average to average for the SWLD. Minimum temperatures were average to below average, with Lake King having 18 nights below 2°C, 10 more than the average for July.
The El Niño in the Pacific Ocean is expected to persist until at least the end of summer (February 2027). Most climate models indicate a positive Indian Ocean Dipole developing from September, along with an increased prevalence of high-pressure systems during winter and spring. Together, these climate drivers are likely to reduce rainfall and bring higher temperatures across the SWLD.

Outlook summary

Rainfall summary

Rainfall since April was average across the majority of the SWLD, with the DPIRD weather station at Pemberton receiving 588 mm of rain. In contrast, the Bureau’s weather station at Ongerup has received only 65 mm.

Figure 1. Rainfall (mm) totals for 1 April to 2 August 2026 in the SWLD. Pemberton recorded the highest total of 482 mm and the lowest total is Ongerup with 43 mm.

Figure 2. Rainfall decile map for 1 April – 2 August 2026 in the SWLD. Indicating decile 1-3 for the majority of the SWLD.

Plant available soil water map

The FAO crop factor method—also known as the FAO crop coefficient method—is a standard approach for estimating crop water use (evapotranspiration), based on the FAO-56 guidelines developed by the Food and Agriculture Organization of the United Nations.

This method assumes that, after germination, a crop progresses through 4 stages of growth. On any given day during the crop’s lifecycle, the crop coefficient for the current growth stage is multiplied by the potential evaporation to estimate plant evapotranspiration. The crop coefficients used have been selected to suit cropping conditions in Western Australia.

The current map, using data up to 2 August, shows the plant available water averaged from 10 soil types (clay, deep loamy duplex, deep sandy duplex, gravel, loamy earth, sand, sandy earth, shallow loamy duplex and shallow sandy duplex) indicates good plant available soil water in the south west corner of the SWLD. Low levels are indicated in the Central Wheatbelt and Great Southern. For more information see DPIRD’s soil water tool.

Figure 3. Plant available soil water map for the SWLD as of 2 August 2026 using FAO crop factor. Indicating low soil water for the majority of 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 Bureau of Meteorology and 175 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 July – DPIRD weather station Lake King had the highest number of nights below 2°C, with 18, which is 10 nights greater than the 2000-2025 average.

Figure 4. Difference in the number of nights below 2°C in July for the 2000-2025 average for the SWLD. For the central grainbelt, July 2026 had a greater number of frost nights than the long term average.

The average number of nights below 2°C for August (2000-2025) indicates that York and Wandering have the highest number of nights below 2°C with 12. Despite the outlook for warmer-than-normal minimum temperatures, frost remains a risk in frost-prone areas. Reduced cloud cover associated with high-pressure systems can increase overnight heat loss, leading to colder surface temperatures and favourable conditions for frost formation.

Figure 5. Average number of nights below 2°C in August for the years 2000-2025 for the SWLD. York and Wandering have the highest number, with 12 nights below 2°C.

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 6. Rainfall outlooks are in 2 sections based on location in the SWLD ̶ the first group includes Central West and Central Wheatbelt forecast districts, while the second group covers 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 climate models shows that 12 models indicate below median rainfall for August 2026. This tendency towards drier than normal conditions continue to September. There is currently no clear model consensus for October and November. For December, there is model consensus for above median rainfall. It is important to note that forecasts are less accurate the further ahead they look.

Figure 7. Single month model summaries of rainfall outlooks for the Central West and Central Wheatbelt forecast districts of the SWLD up to December 2026. Model consensus is for below median rainfall for August and September. Note that forecasts are less accurate the further ahead they look.

Three month

A summary of 17 national and international climate models shows that 14 models indicate below median rainfall for August to October. There is currently no model consensus for spring (September to November) and October to December. For November 2026 to January 2027, there is model consensus for neutral chance of exceeding median rainfall. A neutral chance suggests that extreme wet or dry events are less likely, and a wide range of rainfall amounts remains possible. Note that forecasts are less accurate the further ahead they look.

Figure 8. Three month model summaries of rainfall outlooks for the Central West and Central Wheatbelt forecast districts of the SWLD up to November 2026 to January 2027. Model consensus is for below median rainfall for August to October. Note that forecasts are less accurate the further ahead they look.

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 climate models shows that 12 models indicate below median rainfall for August 2026. This tendency towards below median rainfall continues for September. For October and November, there is model consensus for neutral chance of exceeding median rainfall. A neutral chance suggests that extreme wet or dry events are less likely, and a wide range of rainfall amounts remains possible. There is currently no model consensus for December rainfall. Note that forecasts are less accurate the further ahead they look.

Figure 9: 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 2026. Model consensus is for below median rainfall for August and September. Note that forecasts are less accurate the further ahead they look.

Three month

A summary of 17 national and international models shows that for August to October 2026, 14 models indicate below median rainfall. This model consensus continues through until spring (September to November). For October to December and November 2026 to January 2027, model consensus is for neutral chance of exceeding median rainfall. A neutral chance suggests that extreme wet or dry events are less likely, and a wide range of rainfall amounts remains possible. Note that forecasts are less accurate the further ahead they look.

Figure 10. Three month model summaries of rainfall outlooks for the Lower West, South West, Great Southern, South Coastal and South East Coastal forecast districts of the SWLD up to November 2026 to January 2027. Model consensus is for below median rainfall for August to October. Note that forecasts are less accurate the further ahead they look.

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.