PRISM Precipitation 30Yr Normal 800m Annual (Image Service)

Monthly 30-year 'normal' dataset covering the conterminous U.S., averaged over the climatological period 1981-2010. Contains spatially gridded average annual precipitation at 800m grid cell resolution. Distribution of the point measurements to the spatial grid was accomplished using the PRISM model, developed and applied by Dr. Christopher Daly of the PRISM Climate Group at Oregon State University. This dataset was heavily peer reviewed, and is available free-of-charge on the PRISM website.