USDA Hardiness Zones and Average Annual Minimum Temperature Range

NOTE: The map shown above was published in 1990. Every fifteen years, the USDA puts out a new hardiness zone map. The 2005 map has yet to be published. However, the National Arbor Day Foundation, using the same data the USDA uses, has published a new map (see below) that demonstrates some significant changes that have taken place in the last fifteen years. Clicking on the link above will take you to their website where, among other things, you can view a map highlighting the changes over the last several years.