A two-hour storm unleashed 54mm (2.1in) of rain on Sunday night in Paris, the equivalent of 27 days of rainfall.
Weather services say 49.2mm fell in one hour, the French capital’s heaviest July deluge on record.
Flooding closed 20 metro stations and several were still shut as commuters made their way to work on Monday morning.
Parts of Switzerland were hit by violent winds and hail storms that also caused flooding at the weekend.
Heavy rain began in Paris at 21:00 (19:00 GMT) on Sunday night and Méteo France said the amount that fell was higher than the previous record of 47.4mm set on 2 July 1995. Rain continued to fall heavily on Monday in Paris.
Some areas of the west and around Paris had seen more than a month’s average rainfall between Sunday afternoon and 08:00 on Monday, it said. The western village of Civray saw 86mm in 24 hours.