What Are Climate Normals?
Traditionally, scientists define climate normals as three-decade averages of climatological variables. Since 2010 the batch of 30-year Climate Normals developed and used by NOAA covered the period from 1981 to 2010 and was calculated from observations at approximately 9,800 stations across the U.S. operated by NOAA National Weather Service.
Every 10 years NOAA releases the latest 30 year "normals" or averages, which now cover the period 1991-2020.
