Variation of Lightning over the Bulgarian Black Sea Coast

¹ Faculty of Physics, Sofia University "St. Kliment Ohridski", Sofia, Bulgaria
² National Institute of Meteorology and Hydrology, Branch of Varna, Bulgaria
³ National Institute of Meteorology and Hydrology – Sofia, Bulgaria

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 15 April 2026

Abstract

This study examines the annual, seasonal, and monthly lightning density along the Bulgarian Black Sea coastal zone, as a transitional area between land and sea. Seasonal analysis shows that during winter, spring, and summer, lightning density over the coast is higher than over the Black Sea but lower than over land (Bulgaria). In contrast, during autumn, lightning activity reaches its peak over the Black Sea, while the flash densities over the coast and inland areas become approximately equal. To examine regional differences in detail, the Bulgarian coast is divided into four regions —Shabla, Varna, Sunny Beach, and Primorsko. Primorsko, the southernmost region of the Black Sea coast, has the highest flash density, whereas Shabla, the northernmost region, has the lowest. The monthly analysis indicates that July is the month with the highest flash density when examining lightning activity along the entire Bulgarian Black Sea coast. However, when the coast is divided into smaller regions, the maxima occur at different times for each area: Sunny Beach in May, Shabla and Varna in July, and Primorsko in August. These results highlight the pronounced spatial and temporal heterogeneity of lightning activity along the Bulgarian Black Sea coast and emphasize the importance of conducting analyses at finer, local scales to understand the significance of the influence of factors involved in thunderstorm formation within the specific areas and time periods.