The Louvre and Orsay museums in Paris have moved art works stored underground to safety as the swollen river Seine keeps rising following days of torrential rains that have killed two people.
Floodwaters have forced thousands to evacuate homes and dozens of schools have closed south of Paris.
Earlier this week the army was also called in to rescue stranded motorists on a major highway.
"For the museums, even if fortunately there isn't any flooding of storerooms as of today, there is an automatic process above 5.50 metres to move works in the deepest storerooms higher," Bruno Julliard, Paris' deputy mayor, told France Inter radio on Friday.
The Louvre and the Musee d'Orsay are both home to world-renowned collections.
Julliard said the works in the museums, which overlook the Seine, were not at risk as of early Friday.
Some low lying roads running along the river are underwater and one underground commuter line has been closed.
Officials forecast the Seine could peak at 6 metres in central Paris on Friday, stressing this is still well below the level where it would threaten residents and businesses.
The river reached a record high of 8.6 metres in 1910, when thousands of Parisians had to flee flooded low-lying areas of the city.
Environment Minister Segolene Royal told France 2 television the floods may take several weeks to subside.
"What's going to be even more painful for the families who have lost their homes, the heads of companies who have lost their businesses, the employees who will be unable to go to work, is that the drop in the water level will be very slow," she said.
The retreating waters could reveal further victims, Royal added.
In Evry-Gregy-sur-Yerre, south of Paris, a man on horseback drowned on Thursday, becoming the second fatality. Le Parisien newspaper said the 74-year-old had been trying to cross a flooded field.
