Climate normals are calculated every 10 years and are an average of 30 years of climate data. The calculations are done by the National Climatic Data Center in Asheville, NC. More information can be found at: http://www.ncdc.noaa.gov/oa/climate/normals/usnormals.html

The new 1981-2010 climate normals will be incorporated into our climate text products. The products that will be affected are shown below. Any product that has data that crosses the August 1 implementation date, will use the new 1981-2010 climate normals. Products issued prior to the change date will not be reissued using the new climate normals.