Palmer Drought Severity Index (PDSI)

Palmer in 1965 developed this index as a means of measuring the severity of the drought. It could also be used to evaluate wet situations during which it is referred as Palmer Index (Alley 1984).
As of September 28, 2021 The Climate Data Guide website further explains PDSI as the following

“It is a standardized index that generally spans -10 (dry) to +10 (wet). Maps of operational agencies like NOAA typically show a range of -4 to +4, but more extreme values are possible. The PDSI has been reasonably successful at quantifying long-term drought.



Alley, William M. 1984. “The Palmer Drought Severity Index: Limitations and Assumptions.” Journal of Applied Meteorology and Climatology 23, no. 7 (July): 1100–1109.<1100:TPDSIL>2.0.CO;2.

Dai,, Aiguo, and National Center for Atmospheric Research Staff (Eds). n.d. “Palmer Drought Severity Index (PDSI).” The Climate Data Guide. Accessed September 28, 2021.…


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