Meteorological officials said the rainfall in the regions of Varna and Burgas since Thursday is equivalent to what is received in a month, the BBC reported.
Floodwaters in Varna have risen to a level of 3.2 ft. Cars have been swept away, and hundreds of people have been left without any electricity or food.
Rescue operations have been deployed in the flood-hit areas.
Last month, more than 40 people were killed and 3.8 billion people were affected when the Balkan countries of Bosnia and Serbia were hit by the worst floods in 120 years.
The region in six days received rainfall that it normally gets over a period of three months.
Officials said that about 100,000 houses and 230 schools and hospitals were destroyed in the floods.