The 48-month Standardized Precipitation Index (SPI-48) is a meteorological drought indicator to monitor precipitation anomalies over 48-month accumulation periods and is a proxy indicator for long-term impacts, for example, reduced reservoir and groundwater re...

The 6-month Standardized Precipitation Index (SPI-6) is a meteorological drought indicator to monitor precipitation anomalies over 6-month accumulation periods and is a proxy indicator for medium-term impacts, for example reduced stream flow and reservoir stor...

The 3-month Standardized Precipitation Index (SPI-3) is a meteorological drought indicator to monitor precipitation anomalies over 3-month accumulation periods and is a proxy indicator for immediate impacts of droughts, such as reduced soil moisture, snowpack,...