U.S. national annual precipitation, 1900-1999 (1999 estimated), based on data from the U.S. Historical Climatology Network (US HCN).   For the year 1999 taken as a whole, the United States experienced a near normal year for precipitation, although considerable variability occurred both temporally (i.e., as the year progressed) and spatially (i.e., in different parts of the country).