Historical Palmer Drought Indices
Monthly maps of drought conditions in the contiguous United States as measured by the Palmer Drought Severity Index, Palmer Hydrological Drought Index, Palmer Modified Drought Index, and Palmer Z-Index (Palmer, 1965) are provided for January 1900—March 2021. Animations of any set of monthly maps for any period desired can be viewed by selecting the beginning and ending dates of interest. These maps are provided by the NOAA National Centers for Environmental Information, National Oceanic and Atmospheric Administration.