The amount of summer rainfall provides an indication of the amount of stored soil water at the start of the growing season.
Rainfall deciles are generated using data from 1975 to 2014 (inclusive) for each location.
The graphs are produced using daily rainfall data from the Patched point data set and data from DAFWA's automatic weather stations (AWS). When data for an AWS is unavailable, data from the geographically closest Patched Point station are used. For example, many of the AWS only began recording data recently, so historical data from the closest Patched Point station is used to create pseudo rainfall deciles.
While rainfall to date graphs can help create a narrative for the progress of a given crop and aid key in-season decision-making, other key factors also need to be considered for any given crop to arrive at an accurate picture. These include:
- soil status and characteristics including stored soil moisture, soil water-holding capacity and any barriers to infiltration
- stored nitrogen and other nutrient availabilities
- factors such as non-wetting, water-logging through topography or impermeable layers, leaching or dispersible clays in the soil.
The timing and event intensity of rain during the growing season can also greatly influence the conversion of rainfall to biomass and yield.
To use the tool, first select a weather station from the drop-down list below.
Next, select the summer start date. Usually, the start of summer is set to 1 November of the year prior to the current growing season. This can be changed, for example if a large rainfall event occurred in early November that is unlikely to affect the soil moisture status at the end of summer then you may set the summer start date to exclude that event. The start of summer must be before the start of the growing season. The end of summer will be automatically set as the day before the growing season starts.
Now select the growing season start and end dates. Usually, the growing season is set to be from 1 May to 31 October. However, some growers may find 1 April to 30 September to be more appropriate, depending on their location. The growing season start and end dates must be within the same calendar year.
Cumulative rainfall for the current growing season is shown up to and including the chart date. After the chart date, projected decile finishes are shown. During the growing season, the chart date is usually set to the current date.
Graphs can be downloaded and saved by clicking on the three horizontal lines to the right of the graph title.