Floodwaters in Paris continue to rise with the River Seine due to hit a peak of up to 6.5m (21ft) later on Friday.
The world-famous Louvre and Orsay museums have been closed so staff can move priceless artworks to safety.
The number of dead in the floods has now risen to at least 15 – 10 in southern Germany, two each in France and Romania and one in Belgium.
More downpours are forecast for the weekend across a band of central Europe from France to Ukraine.
Several towns in southern Germany have been devastated. Belgium, Austria, the Netherlands and Poland have also been affected.
Thousands of people have been forced from their homes.
French President Francois Hollande said the weather was a serious climate phenomenon and a global challenge.
He is to declare a state of natural disaster in the worst-hit areas, which will free up emergency funds.
In Paris, emergency barriers have been put up along the Seine, a number of bridges have been closed and tourists boats have been banned from sailing on the river.