Rivers across central Europe have been swelling fast due to rain and melted snow, forcing thousands to flee their homes.
In the Czech Republic, a state of emergency has been declared in seven of the country's 14 regions.
In neighbouring Germany, the army has been called in to shore up flood defences on the River Elbe.
Some houses have been completely cut off near Dresden. But in the historic city itself, waters were rising slower than previously expected.
German authorities say they expect the flooding to peak later on this week, possibly Tuesday.
In Austria, a dam has burst in the village of Duernkrut on the border with Slovakia, forcing mass evacuation.
Hundreds of people have been evacuated in Hungary because of the rising Danube River. The affected areas include the capital, Budapest.
In Slovakia, 200 towns and villages have been affected by the flooding, officials say.
Southern Poland has also been hit, but officials from across the region say the flooding has so far not been as serious as in 2002.