(a)Gridded annual minimum temperature trend as that of 2011-2012, relative to the 1976–2005 mean, over the coterminous USA. (b) Change in trend annual minimum temperature between 1970-1971 and 2011-2012.
Dr. Nir Krakauer has published an article that uses geostatistical analysis of temperatures to figure a new way to compute the difference between the average and the mean temperatures. The Department of Agriculture uses the mean annual temperature over the last few decades (1976-2005) to calculate plant hardiness zones. Dr. Krakauer uses trend estimation over a shorter period of time to deal with the variations we have had in the last few years. He believes the average is already above the mean, so the current map that was revised in January of 2012 is already out of date! The difference is shown in the maps above. It’s interesting to note that the map is all trending warmer but it’s Appalachia that is getting warmer faster! I guess it’s good to lead the nation in some regard…
Here is the map of Kentucky showing our current hardiness zones.
The whole US, and any particular state, can be found at http://planthardiness.ars.usda.gov/PHZMWeb/#