Croatian emergency crews and soldiers are struggling to contain the swollen Sava River that has reached record levels southeast of the capital, Zagreb.
Authorities say water levels Monday by the town of Jasenovac exceeded the highest-ever recorded by some 10 centimeters (4 inches). About a dozen houses in a nearby village are cut off. The Croatian state TV channel HRT says residents have refused to evacuate so emergency crews are delivering food and water by boat.
Experts say the Sava is expected to rise further in the coming days due to fresh snow.
To the east, snow and freezing rain have delayed dozens of flights and some trains in Romania amid an unseasonal cold snap.
Valentin Iordache, the spokesman for Bucharest airports, reported 30 flight delays Monday morning due to the wintry weather. Temperatures were around minus 5 Celsius (23 Fahrenheit). Trains running from Bucharest to the Black Sea port of Constanta and the southern city of Craiova were also delayed.
Weather forecasters issued an amber warning Monday for Bucharest and seven counties in southern and eastern Romania for sleet, snow and black ice.
Winter snow has also hit Germany, Hungary and Britain, among other European nations.