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.
Additionally, the user can click on a location on the map to generate a time series graph of the selected SPI index over the past ten years for that location, and a time series graph that overlays a plot of the SPI over the past calendar year with plots of SPI for the three previous calendar years at that location.
Click and drag on the map to zoom in. To select which administrative boundaries to display on the map (including U.S. states), mouse over the map and select the "Layers" icon. Then use the check boxes that appear to select the corresponding administrative boundaries.
Standardized Precipitation Index
Data:
The Standardized Precipitation Index (SPI) values shown on this page are generated
using monthly precipitation totals at 1.0° lat/lon resolution calculated from a dataset
that combines the retrospective and real-time CPC Gauge - OLR Blended (GOB) daily
precipitation analysis for the globe, accumulated to monthly.
Data Source:
U. S. Climate Prediction Center (U. S. Climate Prediction Center Gauge - OLR Blended daily precipitation analysis)
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