This file area contains version 2 (M4) of the 30-arc-second (~800-m) resolution 1991-2020 PRISM 30-year climate normals datasets in the following gridded (raster) GIS data formats:

 1) BIL (.bil) - Band Interleaved by Line generic raster format
 2) ASCII GRID (.asc) - ArcInfo ASCII GRID raster format

In the filename, "01" = January, "02" = February, and so on.

To download all .bil or .asc grids at once, select the desired "all_files" .zip file.


=== Additional notes about version 2 (M4) of the 1991-2020 30-year normals ===

Version 1 (M3) of the 1991-2020 PRISM monthly and annual 30-year normals was released in November 2021. Version 2 (M4) was released in December 2022 and incorporates a more stable method for adjusting short-period-of-record station averages, as well as additional data quality control measures. Version 3 (M5) was released in February 2024 for tmax, tmin, tdmean, vpdmax, and vpdmin (ppt monthly normals remain version M4). Version 3 (M5) includes adjustments made to a limited number of grid cells along the US West Coast to align with the recently-developed daily normals. Version 3 (M5) supersedes version 2 (M4), which is provided here for archive purposes.

Additional information can be found in the PRISM Datasets Document at https://prism.oregonstate.edu/documents/PRISM_datasets.pdf