Floodwaters in Paris continue to rise with the River Seine due to hit a peak of up to 6.5 metres (21ft) later on Friday, reports BBC News.
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 François 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.
The Seine - which has risen to six metres - has not reached current levels in Paris since 1982, according to the environment ministry.
It previously reached 6.18 metres in 1982, 7.1 metres in 1955 and 8.62 metres in 1910.
It is expected to reach at least 6.3 metres this evening local time and 6.5 metres in a "worst-case scenario", the ministry said, with the water level remaining at those levels throughout the weekend.
Rail operator SNCF has closed a line that runs alongside the Seine in central Paris.
More than 5,000 people have been evacuated from towns in central France since the weekend and 19,000 homes are without power, the AFP news agency reports.
The French Open tennis tournament, meanwhile, could be forced to extend into a third week.