What's new at PRISM
right What does "PRISM" stand for?
PRISM stands for Parameter-elevation Regressions on Independent Slopes Model. Our Documents and Publications page includes scientific papers describing the development and use of PRISM.
right What data formats are available?
Datasets are available on in ASCII or BIL format. ArcGIS can read BIL format (raster data with floating-point numbers). For other types of analysis, ASCII is usually preferable.
right What units are the data values in?
Dataset values are stored in the standard metric units used for climatology: precipitation as millimeters and temperature as degrees Celsius. In creating map graphics, we convert those values to inches and degrees Fahrenheit for you, since most users want maps in those units.
right How Can I Access High-Resolution PRISM Data?
The native grid resolution of the PRISM datasets is 800m, but they have been filtered to 4km resolution for easier downloading and manipulation on this website. The 800m versions of all PRISM datasets, which contain 25x more information, are available to users for a fee. Details on availability, pricing and ordering are found here.
right Where can I find state-level data and maps?
Map images of 1981-2010 mean annual precipitation for each state in the conterminous US are available from our map gallery tab. There are no current plans to produce state-level datasets for download.
right Where is the metadata for datasets located?
The metadata for each data file is included as part of the download package.
right Can I view metadata for datasets in the browser?
This feature is now available from each tab. Note that the format will always say "BIL," since we don't know what format you want until you actually click the Download button.
right What are the terms of use for this data?
See PRISM terms of use for details. This link is also available from each tab.
right What is a BIL file and how do I use it?
BIL is the raster format widely used in climatology. For details on how to use it, see PRISM data formats. This documentation link is also available from each tab. Additional information about the BIL raster format specification will be found at:
    BIL, BIP, and BSQ raster files (Esri ArcGIS Resource Center)
    Extendable image formats for ArcView GIS 3.1 and 3.2 (Esri whitepaper)
    Supported GDAL raster formats (gdal.org) - scroll down to the "EHdr" section
    Band Interleaved by Line (BIL) image file (Library of Congress)
right How can I convert PRISM raster datasets to a different format?
Most GIS software packages, such as Esri's ArcGIS, include the capability to convert raster data in BIL format to multiple other raster (or even vector) formats. For command-line or programmatic conversion of raster data from one format to another, the open source GDAL library is a very useful tool. In particular, the gdal_translate command offers multiple conversion options.
right Where is the Data Explorer for downloading time series data for individual locations?
The Data Explorer is available from the Explorer tab, as well as the homepage.
right When was the data last updated?
Check the data update calendar for the latest information.
right Can I obtain the elevations used by the PRISM model in creating maps?
The elevations are available in map and grid form on the 30-Year Normals page.
right Can I also obtain the station observations used to create the maps?
A station inventory is included in every data package as a CSV file. The inventory includes station ID, name, latitude, longitude, elevation, and network abbreviation (we are not permitted to re-distribute the actual data from these stations). Descriptions of the networks we use and their abbreviations are included in the PRISM datasets documentation; this link is also available from the homepage.
right How should I cite the use of PRISM data or maps?
See PRISM terms of use for details. This link is also available from each tab.
right Where can I find out more about the PRISM model and the use of PRISM data?
See the list of publications about PRISM; a link is available on the homepage.
right How can I download datasets in bulk?
Bulk downloads can be accomplished either using FTP or via our web services. These links are also available from the individual tabs (website sections).
right What data are contained in the downloaded zip files?
Each zip file contains the dataset(s) you selected, plus the associated metadata. The exact contents depend on whether you chose BIL or ASC format; see PRISM data formats for details. This link is also available from each tab.
right Where can I find PRISM climate normals for Alaska?
1981-2010 mean monthly ppt, tmin, tmax, and tmean data for Alaska are available in the Projects area.