Graph showing the Palmer Drought Severity Index for July from 1895–2020

Northern Rockies and Plains (MT, ND, SD, WY, and NE) Palmer Drought Severity Index (PDSI) for July from 1895–2020, illustrating estimated periods of relative dryness in the upper Missouri River Basin. Click on the image for a larger view and source information.

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Last modified
23 August 2021 - 8:29pm