Croatian emergency centres in Bjelovar, Požega, Slavonski Brod and Osijek have had numerous reports of flooded basements and farm buildings following heavy rain and snowfall.
Residents have also reported fallen trees and water spilling from canals and streams after the River Una burst its banks in Hrvatska Kostajnica.
All available forces are on the ground near the Sunja and Una Rivers.
According to officials, they are trying to pump out a large amount of water, while sandbags and barriers have been put in place to prevent further flooding.
