John Keyantash and John A. Dracup evaluate drought indices to assess drought severity. Droughts are the world's most costly natural disasters, causing $6–$8 billion in annual damages. Quantifying drought is challenging, and many indices exist. The paper evaluates six indices based on criteria like robustness, tractability, transparency, sophistication, extendability, and dimensionality. Two Oregon regions, the Willamette Valley and North Central, were tested from 1976–1999. The Willamette Valley is moist with consistent winter precipitation, while the North Central region has moist winters and dry summers. Both have distinct drought types. Meteorological drought indices include precipitation anomalies, rainfall deciles, the Palmer Drought Severity Index (PDSI), the Drought Area Index (DAI), the Rainfall Anomaly Index (RAI), and the Standardized Precipitation Index (SPI). The PDSI is a dimensionless index measuring moisture supply, but it has limitations in regional comparability and ignores snowfall. The SPI is more flexible and probabilistic, using precipitation data to assess drought severity. It is recommended over the PDSI for its broader applicability. Hydrological drought indices include total water deficit, cumulative streamflow anomaly, the Palmer Hydrological Drought Severity Index (PHDI), and the Surface Water Supply Index (SWSI). The total water deficit measures drought severity as the product of duration and magnitude. The PHDI is similar to the PDSI but has stricter criteria for drought termination. The SWSI accounts for snowpack and delayed runoff, making it suitable for mountainous regions. Agricultural drought indices include the Crop Moisture Index (CMI), the Palmer Moisture Anomaly Index (Z index), and computed soil moisture. The CMI tracks short-term moisture changes but is not suitable for long-term drought. The Z index is better for agricultural drought but is complex. Computed soil moisture is a numerical model-based index that assesses soil water balance but lacks a national monitoring network. The evaluation criteria ranked the indices based on their usefulness for drought assessment. Rainfall deciles, total water deficit, and computed soil moisture were top-ranked for meteorological, hydrological, and agricultural droughts, respectively. The SPI was also highly valued for meteorological drought. The paper highlights the importance of selecting drought indices that are robust, transparent, and applicable across different regions and drought types.John Keyantash and John A. Dracup evaluate drought indices to assess drought severity. Droughts are the world's most costly natural disasters, causing $6–$8 billion in annual damages. Quantifying drought is challenging, and many indices exist. The paper evaluates six indices based on criteria like robustness, tractability, transparency, sophistication, extendability, and dimensionality. Two Oregon regions, the Willamette Valley and North Central, were tested from 1976–1999. The Willamette Valley is moist with consistent winter precipitation, while the North Central region has moist winters and dry summers. Both have distinct drought types. Meteorological drought indices include precipitation anomalies, rainfall deciles, the Palmer Drought Severity Index (PDSI), the Drought Area Index (DAI), the Rainfall Anomaly Index (RAI), and the Standardized Precipitation Index (SPI). The PDSI is a dimensionless index measuring moisture supply, but it has limitations in regional comparability and ignores snowfall. The SPI is more flexible and probabilistic, using precipitation data to assess drought severity. It is recommended over the PDSI for its broader applicability. Hydrological drought indices include total water deficit, cumulative streamflow anomaly, the Palmer Hydrological Drought Severity Index (PHDI), and the Surface Water Supply Index (SWSI). The total water deficit measures drought severity as the product of duration and magnitude. The PHDI is similar to the PDSI but has stricter criteria for drought termination. The SWSI accounts for snowpack and delayed runoff, making it suitable for mountainous regions. Agricultural drought indices include the Crop Moisture Index (CMI), the Palmer Moisture Anomaly Index (Z index), and computed soil moisture. The CMI tracks short-term moisture changes but is not suitable for long-term drought. The Z index is better for agricultural drought but is complex. Computed soil moisture is a numerical model-based index that assesses soil water balance but lacks a national monitoring network. The evaluation criteria ranked the indices based on their usefulness for drought assessment. Rainfall deciles, total water deficit, and computed soil moisture were top-ranked for meteorological, hydrological, and agricultural droughts, respectively. The SPI was also highly valued for meteorological drought. The paper highlights the importance of selecting drought indices that are robust, transparent, and applicable across different regions and drought types.