PHZM GIS Data

Official USDA Plant Hardiness Zone Maps for the Conterminous United States, Alaska, Hawaii, and Puerto Rico

Climate Source is the exclusive public distributor of digital GIS versions of the U.S. Department of Agriculture’s Official 2012 Plant Hardiness Zone Map (PHZM). This PHZM data set provides 1976-2005 mean extreme annual minimum temperature in grid or shapefile formats, at an enhanced, effective resolution of approximately 400 m (15 arc-seconds) for the conterminous United States, 200 m (7.5 arc-seconds) for Hawaii and Puerto Rico, and 2 km (1.25 arc-minutes) for Alaska. The shape files are presented as 5°F half-zone classifications in an easy-to-use format. The grids provide actual temperature values, giving sub-zonal precision suitable for scientific usage. Grids and shapefiles are available by state or region.

The USDA selected the PRISM Climate Group at Oregon State University, the same group responsible for other Climate Source data sets, to perform the mapping of this important series of maps. The group employed the latest version of the PRISM climate mapping system, a highly regarded world-class climate mapping technology. Data used in the interpolation process consisted of a comprehensive collection of nearly 8,000 carefully screened stations from major observing networks in the US, Canada, and Mexico.