The SPEI is a multiscalar drought index based on climatic data. It can be used for determining the onset, duration and magnitude of drought conditions with respect to normal conditions in a variety of natural and managed systems such as crops, ecosystems, rivers, water resources, etc.
A global real-time drought monitoring system based on the SPEI is operative. It provides global SPEI maps and data for the entire earth at a spatial resolution of 0.5º.
A global 0.5-degrees gridded SPEI dataset for the period 1901-2011. Download SPEI time series for a given location, or get the full dataset.
The SPEI R package has been developed to help computing SPEI time series under various data scenarios. The package contains also a number of auxiliary functions to help analyze SPEI data.