Purpose. The purpose of the study is to consider both the features of storms in the attenuation stage as a factor in the coastal profile restoration after storm erosion, and a potential cause of seasonal deformations.

Methods and Results. Seasonal morphodynamics of accumulative coastal areas was studied in the regions both of the Vistula Spit (South-Eastern Baltic) based on the monitoring measurements of coastal profile performed by the employees of the Shirshov Institute of Oceanology, RAS, from May 2019 to March 2022 and the Oktyabrskaya Spit (western Kamchatka) using the measurement data taken in 2010–2011. Two indices describing the storm structure are used: the ratio of the attenuation stage duration to the total storm duration R_t, and the ratio of the median value of storm wave height during the attenuation stage to the peak wave height of the storm event R_Hs. The variations in R_t and R_Hs during a year are statistically analyzed based on the ERA5 long-term wave reanalysis data. It is found that the R_t index does not tend to change on a seasonal scale. When the R_Hs index is close to one and changes slightly during a year, the coastal profile does not experience seasonal changes. If R_Hs changes in course of a year decreasing significantly during the period of more intense waves, the coast experiences seasonal changes.

Conclusions. The variations in wave intensity during a year do not always result in the change of average position of the coastal profile. The key factor may consist in the seasonal trends in wave parameter changes within a storm cycle. The proposed index R_Hs can be regarded as a criterion for the behavior type of sandy coasts on a seasonal scale.