The following formats are used for data and graphics available on this website. Be sure to acquaint yourself with our terms of use, which explain how to acknowledge any use of our data.
Map Graphics. All map graphics are PNG files, an image format that supports lossless data compression. PNG images are viewable by all web browsers and image viewing/processing software.
Metadata. Each graphic or data file is accompanied by FGDC-compliant metadata formatted as XML. The FGDC metadata format is the standard for geospatial data, and XML is the preferred format since it can be utilized by many types of software.
Gridded Data. All gridded datasets are bundled with the corresponding ancillary files and compressed as .zip files. Virtually all current operating systems provide full support for .zip files, and it should be straightforward to extract the files either with no command at all (up-to-date Windows and Mac systems) or using the unzip command (Linux).
File Naming Convention
Within each .zip file, individual files follow this convention:
Naming scheme: prism_<var>_<region>_<resolution>_<time period>.<ext>
Example: prism_ppt_us_25m_20250312.zip (ppt data for CONUS at 4km resolution, for the day 12 March 2025)
| Component | Values/Meaning |
|---|---|
| <var> |
Precipitation, temperature, and humidity variables (available as both 30-yr normals and time series data): ppt (precipitation); tmin, tmean, tmax (minimum/mean/maximum temperature); tdmean (mean dewpoint); vpdmin, vpdmax (minimum/maximum vapor pressure deficit) Solar radiation variables (available as 30-yr normals): solclear (clear sky solar rad), soltotal (total solar rad), solslope (sloped surface solar rad), soltrans (cloud transmittance) |
| <region> | us, ak, hi, pr (Corresponding to: CONUS, Alaska, Hawaii, Puerto Rico) |
| <resolution> | 15s, 30s, 25m (Corresponding to: 400m, 800m, 4km) |
| <time period> |
For normals: <mm> = numerical designation for month (01 for January, etc.) annual = cumulative annual values For monthly data: <yyyymm> = numerical designation for year and month <yyyy> = cumulative annual values for year For daily data: <yyyymmdd> = numerical designation for day |
Files That Comprise a Grid
All downloadable datasets are made available in the COG (Cloud Optimized GeoTIFF) raster data format. Each COG grid is composed of several different file types:
| File extension | File content |
|---|---|
| .tif | COG (Cloud Optimized GeoTiff) raster dataset |
| .prj | Spatial projection information |
| .stx | Raster statistics, such as minimum and maximum values |
| .xml | FGDC-compliant metadata describing the raster dataset |
| .aux.xml | Raster statistics in the format expected by Esri software |
| .info.txt | Internal information about the creation of the raster dataset |
| .stn.csv | Included in many PRISM raster datasets, this file contains a list of stations that contributed to the modeling of that particular dataset |
