Winter Chill for 2025 for South West Western Australia
Pomewest Project Manager Susie Murphy White reports
The trend for 2025 for winter chill accumulation is more positive than last season but still tracking along in the lowest 10% of years. The first chill portions accumulated were about 2 weeks ahead of the warm winter of 2024. As the first chill portions for Bickley and Donnybrook were recorded in mid-May, with Manjimup a month earlier in mid-April. For all locations we are still reached the70% of the average winter chill portions required to break dormancy. Although seasonal conditions were cooler and wetter than the previous season temperatures, June maximum temperatures were 1-3°C above average, while minimum temperatures were about average. Even though the last couple of weeks have been good for winter chill accumulation, the warm autumn and early winter temperatures have set the season up for low winter chill year again. Hopefully the warm spring weather is still a few more weeks away when the buds start to move!
Table 1. Winter chill portion accumulation data for South West Region of WA. 2025 Winter chill portions calculated on 24th July 2025. Average chill portions 1994-2023.
Further investigation of previous low chill years can be done using the My Climate View resource My Climate View developed by the Climate Services for Agriculture program funded by the Australian Government’s Future Drought Fund (FDF). As shown in the past and projected winter chill accumulation graph in figure 1, the chill accumulation is set to decline in the future.
Figure 1. Past and projected future chill accumulations for Manjimup, My Climate View
Further investigation of previous low chill years can be done using the My Climate View resource My Climate View developed by the Climate Services for Agriculture program funded by the Australian Government’s Future Drought Fund (FDF). As shown in the past and projected winter chill accumulation graph in figure 1, the chill accumulation is set to decline in the future.
Based on this week’s weather data for Manjimup and surrounding areas from 21st July to 25th July, 2025, the following demonstrates how conditions have supported winter chill accumulation. Winter chill portion accumulation typically occurs when temperatures stay consistently between 2°C and 14°C.
Manjimup Thursday (24th July): 10.8°C Min temps: As low as 3–6°C Max temps: Mostly between 10–14°C 4 days in the chill zone: Chill accumulation strong, with only 21st July reaching 16°C which may have slightly reduced chill accumulation.
Pemberton Thursday (24th July): 10.8°C 2 days in the chill zone: Suggests less consistent cold compared to Manjimup
Donnybrook Thursday (24th July): 13°C 2 days in the chill zone: Warmer overall, less chill accumulation
Newlands Thursday (24th July): 10.9°C 4 days in the chill zone: Moderate chill accumulation
Bickley Thursday (24th July): 11°C Minimum temperatures: Consistently around 3–6°C Maximum temperatures: Hovering near 11°C daily. Last 7 days in the chill zone: Good chill accumulation.
Bickley’s chill profile is very similar to Manjimup, possibly even more stable due to its elevation and consistent cool maximums
Figure 2. Winter Chill Portion accumulation in Manjimup 24th July 2025.
Figure 3. Winter Chill Portion accumulation in Donnybrook 24th July 2025.
Figure 4. Winter Chill Portion accumulation in Bickley 24th July 2025.