Standardized Precipitation Maps
The Standardized Precipitation Index (SPI) was developed for the purpose
of defining and monitoring drought. Among others, the Colorado Climate
Center, the Western Regional Climate Center, and the National Drought
Mitigation Center use the SPI to monitor current states of drought in
the United States.
For more information on the methodology behind SPI, click on either
a PostScript version or
an Adobe PDF version of Chapter 3 of Dan Edwards' Masters Thesis.
This document details the mathematics used in SPI calculation.
For source code for a simple SPI program, click here for
Unix tar format or zip format.
Projected Conditions at 0.2 Probability Level
Projected Conditions at 0.5 Probability Level
Projected Conditions at 0.8 Probability Level
Data Access Links > Current Weather: Colorado
Water Year Data:
Long Term Climate: Colorado