Rain events can be characterized by rain drop size distribution (DSD) that denotes the number of drops as a function of diameter per unit size interval and per unit volume of space. DSD (at ground level) describes the microstructure of precipitation during different phases of rain varying both spatially and temporally. DSD can be influenced by the nature and origin of rain. The present study investigates the role of continental and maritime airflow in influencing the precipitation features near the land-sea boundary. The data of the rain DSD used in the present analysis are collected from a ground-based disdrometer located at Kolkata, India, near land-sea boundary during the year of 2011–2017. The dataset is divided into two categories, namely, maritime and continental rainfall, based on the airflow trajectories associated with rain events exclusively from Bay of Bengal or land region in the west of Kolkata as derived from TRAJSTAT software. The events with trajectories extending both over land and sea region are excluded for the present study. Variations of the DSD parameters using the gamma model are presented showing the abundance of smaller drops during maritime rain events whereas dominance of larger rain drops in the case of the continental rain events. The Z-R relations are also found to be significantly different for these two types of rain. The present study reveals the microstructures of rain at a location where the influences of both land and sea climatic features prevail. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.