PDSI Index - Current situation - September 2026

According to the PDSI index, between late August and late September 2026, there was a very significant worsening of the meteorological drought conditions in mainland Portugal, reflected both in an increase in the affected area and in the intensification of drought classes.

The normal, moist conditions that prevailed in the North and Center in August virtually disappeared, being replaced mainly by mild to moderate drought classes. At the same time, drought conditions intensified in the South, with more widespread moderate and severe drought classes, particularly in the interior.

Percentage distribution by PDSI index classes:

• Normal: 0.7
• Mild Drought: 38.6
• Moderate Drought: 44.2
• Severe Drought: 16.5

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