Calculating the regime of waves, in accordance with recommendations of the World Meteorological Organization, requires a database covering not less than 30 years. Continuous measurements for a time interval as long as that are available only for a small number of coastal water areas. Commonly such data are derived from calculations by numerical (spectral) hydrodynamic models of wind-induced waves. The inputs in such cases are data on wind obtained by reanalysis. However, reanalysis cannot be applied to calculations for some seawater areas without pretreatment. Data on the Caspian Sea are used to demonstrate an approach to correcting NCEP/NCAR reanalysis data. The results of the application of this procedure are given.