Valls said after a government meeting that "return to normality will take time" and that "solidarity is called for."
He said the fund will be credited with "several tens of thousands euros" (dollars) to provide quick help to people with no resources.
About 7,000 French homes remained without electricity today and the Louvre museum will stay closed until tomorrow.
In Paris, several train stations and roads remained closed and emergency crews were pumping water out of a key highway interchange.