Despite the large distance, the most important climate-forming factor is the Atlantic Ocean through the atmospheric circulation of the Icelandic cyclone and the Azores anticyclone, which bring cool and rainy weather in summer and relatively mild weather with abundant snowfall in winter. The influence of the Mediterranean Sea is strongest in the southern parts of Bulgaria, mainly through the Mediterranean cyclones. Due to its small area, the influence of the Black Sea only affects a 30–40 km long strip along the coastline, mainly in summer, when the daily breeze circulation is most pronounced.