Skip to main content

Drought Planning Toolbox

Go Search
Loans & Grants
Water Management
Technical Resources
Public Information
About Us
Home > Technical Resources > Drought Planning Toolbox > DroughtIndices > Standard Precipitation Index (SPI)  

DroughtIndices: Standard Precipitation Index (SPI)


Standard Precipitation Index (SPI) 

Index Website

Index Description

The SPI was developed at the Colorado Climate Center as a tool for defining and monitoring drought and is a robust index for describing drought patterns. The SPI is based only on current and historical precipitation data for a particular location. The computed SPI values are proportional to precipitation deviation from the “average” (surplus or deficit).The SPI is computed for several time scales, ranging from one month to 24 months, to capture the various scales of both short-term and long-term drought.  The SPI can be used to identify the beginning and end for each drought, as well as an intensity level for each month in which the drought occurs.

Index Use

Created at 11/15/2010 3:31 PM  by System Account 
Last modified at 11/16/2010 11:28 AM  by System Account