From the high mountains to the Danube river and eastward to the Black Sea coast you will find both in summer and winter differences of upto 20 degrees.
The predominant climate in Bulgaria is moderate and transitional continental. (2,000 to 2,400 hours of sunlight per year).
Four seasons. Dry and hot summer.
The Summer temperature ranges between 16° and 30° C.
The average Winter temperature ranges between -15° and 6° C.
