Central and southern Slovenia are put on weather alert on Friday when successive days of heavy rain is forecast to continue until Saturday night.
Rivers keep rising since Thursday while more than 600 houses situated at the southwest of Ljubljana and the outskirts of the capital have been flooded, local mass media reported.
South and central Slovenia received between 20 and 70 litres of rain per square metre in the past 12 hours, according to the Environment Agency.
Some places should brace for downpours with the amount of rain in parts of the south possibly exceeding 80 l/m2 by Saturday night, weather forecast said.
More than 1,200 fire fighters and volunteers have been mobilized to fight the flood and provide disaster relief.
Slovenia, with an area of just over 20,000 square kilometers, has been frequently flooded in recent years, thus having inflicted heavy losses on many farmers and many house owners.