The modern approach for wind wave climate estimation is presented. The input for wave calculation by numerical models is reanalysis data. For extreme wave estimation in severe storms the reanalysis data has to be corrected (by regression model as an example). For calculations of wind waves in Caspian Sea SWAN model was used. 40 years continues calculations were made. At the first stage calculations performed for whole the sea, and then these data were used as the first input for detailed calculations for shallow the Northern Caspian Sea. The estimates of extreme wave heights were presented for different depths.