For gardeners who are thinking about spring planting season (that would be all of us), there is a new USDA Plant Hardiness Zone Map. Here is the section that covers southern Maine:
The 2012 USDA Plant Hardiness Zone Map is the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. The map is based on the average annual minimum winter temperature, divided into 10-degree F zones.
For the first time, the map is available as an interactive GIS-based map, for which a broadband Internet connection is recommended, and as static images for those with slower Internet access. Users may also simply type in a ZIP Code and find the hardiness zone for that area.
For various reasons, this updated map shows that parts of southern York County have “moved” from Zone 5b to Zone 6a, which, incidentally, is the same zone as half of Missouri and most of Ohio.