This dataset includes polygon boundaries for contours of average annual precipitation, measured in inches. The data represent the average or normal amount of precipitation, based on the most recent standard 30-year climate period from 1991-2020.

These data represent average annual precipitation amounts in Utah for the 1991-2020 period. The dataset was created to provide a generalized polygon alternative to the original raster data that is typically used in the scientific community. The polygon version makes it easier to work with for GIS users in Utah.

The purpose of this dataset is to provide generalized average annual precipitation data for the state of Utah, to be used for general analysis and cartographic purposes.

Each polygon feature in this dataset represents a 1-inch range of average annual precipitation. The data has attributes for the minimum (min_inches) and maximum (max_inches) average annual precipitation found within a particular polygon, along with a generalized attribute (inches), which is equal to min_inches. For example, a polygon with min_inches = 15 and max_inches = 16, has average annual precipitation values between 15 and 16 inches. For more precise data at a given point location, users are encouraged to obtain the original source raster data from the PRISM Group's 30-Year Normals , opens in a new tab page.

UGRC derived this dataset from a nationwide analysis completed by the PRISM Group , opens in a new tab at Oregon State University. The original raster dataset (approximately 800m resolution) was downloaded from the PRISM site, clipped to a buffer around Utah, and converted from millimeters to inches. Then it was contoured for every whole inch as an interval of 1 inch, to create a polygon dataset. The polygon data was then projected into UTM NAD83 Zone 12N (WKID: 26912), and clipped to the state of Utah boundary.