The USDA highlights their web ability to provide data by zip code and refinements which take into account more weather controlling elements such as mountains and bodies of water. This should allow more precision in plant hardiness decisions.
Seth Borenstein of the Associated Press points to zone changes indicative of global warming whereas USDA denies the soundness of using temperature lows as a predictor of change. He points out that "nearly entire states, such as Ohio, Nebraska, and Texas are in warmer zones."
