The atmospheric water vapor flux over North America and the Central American Sea (Gulf of Mexico and Caribbean Sea) has been investigated for the period May 1, 1961–April 30, 1963, as part of a more general study of the water balance of these areas. Mean monthly values of the total vapor flux components are analyzed and the more important aspects of the regional vapor flux climatology are discussed and illustrated by maps and cross-sections. Additional insight into the seasonal march is obtained from the computation of the total monthly vapor flux across selected regional boundaries. Major features of the North American total vapor flux field previously described by Benton and Estoque are confirmed, but the more extensive data used in this study bring out additional significant detail, particularly over the southern United States. Important diurnal variations are found in the flux field, particularly during the summer south of 50° N. These result primarily from diurnal variations in the average m... Abstract The atmospheric water vapor flux over North America and the Central American Sea (Gulf of Mexico and Caribbean Sea) has been investigated for the period May 1, 1961–April 30, 1963, as part of a more general study of the water balance of these areas. Mean monthly values of the total vapor flux components are analyzed and the more important aspects of the regional vapor flux climatology are discussed and illustrated by maps and cross-sections. Additional insight into the seasonal march is obtained from the computation of the total monthly vapor flux across selected regional boundaries. Major features of the North American total vapor flux field previously described by Benton and Estoque are confirmed, but the more extensive data used in this study bring out additional significant detail, particularly over the southern United States. Important diurnal variations are found in the flux field, particularly during the summer south of 50° N. These result primarily from diurnal variations in the average m...