The riverside museum — the most visited in the world, home to everything from the Mona Lisa to priceless Egyptian artefacts, took the radical action after days of torrential rain in the French capital.
The Musee d’Orsay, which faces the Louvre on the opposite bank of the river, closed early on Thursday to put its own “protection plan” into place.
Its galleries hold the world’s greatest collection of Impressionist masterpieces, including the finest paintings by Renoir, Manet, Van Gogh and Degas, as well as 24 works by Gauguin.
“The aim is to move works situated in areas vulnerable to flooding to safety by moving them to higher floors,” the Louvre said in a statement.
Only hours before, the museum had played down the threat to its vast underground stores which are fitted with anti-flood pumps and sealed waterproof doors.
But as the Seine swelled to more than five metres (16 feet) above its usual levels Thursday, and burst its banks in places, its management decided to close its galleries entirely.
The Musee d’Orsay said a crisis management team had been put in place to organise the moving of its most vulnerable treasures to its upper floors if the Seine rises more than 5.5 metres (18 feet).
By some estimates, the river could rise 6 metres above its usual height Friday. According to the Musee d’Orsay, both institutions have detailed emergency flooding plans.
These give the Louvre 72 hours and the Musee d’Orsay 96 hours to get works held in their underground reserves to safety. Both museums have organised drills this year to deal with floods.
In one such exercise in March, the Louvre evacuated the whole of the underground section of its new Islamic art galleries in a day.
The Louvre has plans to move its vast stores from its vulnerable riverside site to a new building near its satellite museum at Lens in northern France in 2019.
The Musee d’Orsay has already moved many of its reserves off-site, and says it has an emergency generator on its roof in case floods cut the electricity supply to the building.