🇧🇬Bulgaria

Bulgaria's climate stretches across 41°14′–44°13′N in southeast Europe, with a Black Sea coastline defining the eastern border. The terrain is complex: the Danubian plain dominates the north, the Balkan Mountains (Stara Planina) run east–west across the center, and the Rhodope, Rila, and Pirin ranges rise in the south, crowned by Mount Musala at 2,925 m—the highest peak in the Balkans. This produces a transition between humid continental (Dfb) in the interior, humid subtropical (Cfa) along the Black Sea coast, and Mediterranean influence (Csa) in the southwest river valleys.

Sofia, at 550 m elevation, records average January temperatures around −1°C and July near 21°C, with annual precipitation around 620 mm. The Black Sea coast, exemplified by Varna, is milder—January near 3°C and August around 24°C—but drier at roughly 470 mm annually.

Plovdiv in the southern Maritsa valley regularly experiences summer temperatures exceeding 35°C, while mountain stations like Botev and Musala remain below freezing for four or more months per year with snowpack often exceeding 150 cm. Bora-style cold northerly winds affect the Black Sea coast in winter, föhn winds descend from the south-facing slopes of the Balkans, and convective summer storms strike the highlands with particular severity.

Our archive covers 6 Bulgarian cities with daily ERA5 reanalysis data going back to 1940. The warmest July averages occur in Plovdiv, around 30.3°C, while Sofia records the coldest January nights near −4.6°C. Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 1.7°C.