The levels of the River Seine in Paris have started dropping slightly after reaching a 34-year high on Friday.
The river level rose to 6.1m (20ft) above its normal height overnight.
Floods also forced parts of the metro system and major landmarks to close, while the Louvre and Orsay museums were shut while staff moved art to safety.
Despite the water level falling on Saturday morning, Paris remains under the second-highest alert, which warns of a “significant impact”.
Forecasters had warned the river could reach as high as 6.5m above it normal level.
France’s environment ministry said the floods now appeared to have peaked and would remain stable over the weekend before retreating further.
Prime Minister Manuel Valls said four people had died and 42 were injured across the country.
Some 17,000 homes in and around Paris remain without electricity.