This map shows values of the monthly Standardized Precipitation Index (SPI) for a user-selected accumulation period (3, 6, 9, or 12-month) for the globe, based upon observed monthly precipitation totals from the Climate Prediction Center's (CPC) Gauge - OLR Blended (GOB) daily precipitation analysis (combined retrospective and real-time, accumulated to monthly). The SPI maps provide an indication of short-term to longer-term wet (green, positive SPI) or dry (yellow to red, negative SPI) conditions based upon precipitation alone. The negative half of the color scale uses the same colors and thresholds of SPI corresponding to the percentiles associated with the D0 (30%tile) to D4 (2%tile) drought intensity categories used in the U. S. Drought Monitor.

This tool displays maps of probabilistic forecasts of the Standardized Precipitation Index (SPI, for 3, 6, 9, or 12-month accumulation periods) for the globe based on monthly precipitation predictions from 6 NMME models and the initial observed condition. For locations and seasons where NMME does not show demonstrable skill, the SPI forecasts are based on a persistence methodology.