PDSI Index - Current situation - August 2025

According to the PDSI index at the end of August, there was an increase in the area experiencing meteorological drought, with almost the entire territory in this situation. There was also an increase in intensity, with more regions in the moderate drought class, rising from 5% of the territory in July to 21% at the end of August, covering the north-west region, the central-south interior region and some locations in the interior of the Lower Alentejo.

The percentage distribution by PDSI index classes in mainland Portugal at the end of August is as follows:

• 0.6% in the normal class
• 78.5% in the mild drought class
• 20.9% in the moderate drought class

Drought monitoring

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PDSI Index (Palmer Drought Severity Index) was developed by Palmer (1965) and implemented and calibrated for mainland Portugal (Pires, 2003).

This index is based on the concept of the water balance taking into account data on the amount of precipitation, air temperature and available water capacity in the soil and allows the detection of periods of drought by classifying them in terms of intensity (weak, moderate, severe and extreme).

Last 12 month evolution