A database covering at least 30 years is required for calculation of the wind-induced waves mode in accordance with recommendations of the World Meteorological Organization. Continuous measurements of wind-induced waves for this period of time are missing or available only for a limited number of offshore strips. Typically this information is a result of calculations based on numerical (spectral) hydrodynamic models of the wind-induced waves while input data is information regarding wind from reanalyzes. Reanalysis can be used for calculation of wind-induced waves without any preliminary processing but not for all offshore zones. The Caspian Sea is used as an example to demonstrate an approach to revision of the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data and study results are provided.