Short term dryness indicator

Improvement in Relative Soil Water values across NSW

• Short-term indicators are highlighting the influence of the above average rainfall received during May, with soil moisture levels above 40% for much of NSW, for the 21 days until 31 May 2026.
• It is important to cross reference the short-term dryness indicator with the SWI to assess if this is a temporary change or a more sustained shift in conditions.

The 21-day Relative Soil Water indicator is a short-range physical drought indicator for detecting rapid drying events. It is calculated by using the 21-day rolling mean of daily modelled rootzone soil moisture (mm) and normalises that, relative to the water holding capacity (drained upper limit) of the soil at that location.

While it is an indicator that is a closer reflection of field conditions at the time of observation, it is also more volatile (changes rapidly). This contrasts to the SWI which is less sensitive to short range variability and designed to detect long term seasonal conditions.