France is to declare a state of natural disaster in areas worst hit by flooding in recent days, President François Hollande said, reports BBC News.
The measure frees up funds, with some towns in central France suffering their severest floods in decades.
In Paris the Seine continues to rise, prompting the closure of a metro line running through the city centre.
Heavy rains across Europe have left at least 10 people dead, most of them in Germany.
More downpours are forecast right through the weekend across a band of central Europe from France to Ukraine, with as much as 50mm (2in) of rain falling in some parts in just a few hours.
Emergency barriers are being put up along the Seine, which burst its banks in places. Its levels are forecast to peak overnight.
The most-visited museum in the world, the Louvre, is closing on Friday as a precaution. Another major attraction, the Musée d'Orsay, is shutting its doors early on Thursday.
Rail operator SNCF announced the closure of the RER C line, which runs alongside the Seine in central Paris from 16:00 local time.
About 25,000 people are without power in Paris and central France.
In Nemours, 3,000 people have been evacuated from the town centre.
The town's Loing river, a tributary of the Seine, now has levels not seen since the devastating floods of 1910.
"The centre of town is totally under water. All the businesses have been destroyed," said mayor Valérie Lacroute.
Six weeks' worth of rain has fallen in three days in the Loiret department.
Other news from France:
- Fire services found the body of an 86-year-old woman in her home in Souppes-sur-Loing
- The French Open tennis tournament could be extended into a third week
- Floods also cut off the getaway of two shop robbers in the town of Fleury-les-Aubrais. They fled their car and tried to make a swim for it, but were arrested