U.S. Drought Monitor Monthly Modified Palmer Drought index Self Calibrated PDSI 7-Day Percent of Normal Precipitation 30-Day Percent of Normal Precipitation 60-Day Percent of Normal Precipitation 7-Day Temperature Anomaly 30-Day Temperature Anomaly 60-Day Temperature Anomaly One-Month SPEI 2-Month SPEI 3-Month SPEI 6-month SPEI 12-Month SPEI 24-Month SPEI One-Month Standardized Precipitation index (SPI) 2-Month SPI 3-Month SPI 6-Month SPI 12-Month SPI 24-Month SPI